Problems with 12V and 5V lines on a PC ATX supply

On Friday, February 21, 2020 at 11:12:12 AM UTC-8, John Larkin wrote:
Do PC supplies do some sort of averaged or compromise or nonlinear
feedback?
Click to expand...

I'm working on a box right now that uses a 250W redundant ATX supply
(at the customer's request):

https://www.surestar.com.tw/product/47

My application only needs +12V, and when I took one of the PSUs apart for
evaluation, I saw that only the low-current +5 standby and +12 rails are
actually generated by the ATX supplies. +5, -12, and +3.3 are generated
from +12 by outboard regulators on a separate board.

What's frustrating is that while this particular supply works just fine
with no load on any of the rails, the manual calls for 1A minimum loads
on +3.3, +5, and +12, and 500 mA on +5 standby.

This is for $$$, not a homebrew hack, so I have no choice but to follow
the manufacturer's specs and bolt three big resistors to the chassis to
burn almost 10W for no reason.

The other weird thing about redundant power supplies is that there is no way
for the supply to signal that one of the supplies has failed. There's a
loud alarm buzzer, of course, and LEDs to indicate the status of both
supplies, but the power-good signal stays high when you unplug one of them,
and the server motherboard has no way to know anything is amiss.

So I did hack it to the extent of replacing the status LEDs with connections
to the controller. I feel like I'm overlooking something obvious here,
because most of these supplies end up in data center racks that are hundreds
of yards away from the nearest human. Do Google and Amazon just send
somebody down the aisles every so often to listen for buzzers...?

-- john, KE5FX
 
On Monday, February 24, 2020 at 6:05:27 PM UTC-8, John Miles, KE5FX wrote:
So I did hack it to the extent of replacing the status LEDs with connections
to the controller. I feel like I'm overlooking something obvious here,
because most of these supplies end up in data center racks that are hundreds
of yards away from the nearest human. Do Google and Amazon just send
somebody down the aisles every so often to listen for buzzers...?
Click to expand...

Actually, looking back at the data sheet, there's supposed to be a
separate TTL signal cable, which for some reason the supplies I received
didn't have.

WTF, that's kind of annoying.

-- john, KE5FX
 
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

"Commander Kinsey" <CFKinsey@military.org.jp> wrote in
news:eek:p.0gim98w6wdg98l@glass:

On Fri, 21 Feb 2020 01:50:39 -0000,
DecadentLinuxUserNumeroUno@decadence.org> wrote:

"Commander Kinsey" <CFKinsey@military.org.jp> wrote in
news:eek:p.0gbbg6ebwdg98l@glass:

On Fri, 21 Feb 2020 00:17:00 -0000, bitrex <user@example.net
wrote:

On 2/20/20 7:11 PM, Commander Kinsey wrote:
On Thu, 20 Feb 2020 23:41:11 -0000, bitrex <user@example.net
wrote:

On 2/20/20 5:55 PM, Commander Kinsey wrote:
On Thu, 20 Feb 2020 22:27:48 -0000, Lasse Langwadt
Christensen <langwadt@fonz.dk> wrote:

torsdag den 20. februar 2020 kl. 23.16.57 UTC+1 skrev
Commander Kinsey:
Why do (cheap? expensive ones may be better) PC ATX power
supplies need current drawn from the 5V line to make the
12V line work correctly?

I have a PC with 3 graphics cards running scientific
applications. I acquired three old graphics cards that
take about 300W each, and have loads of cheap (CIT) PSUs
that are rated at 650W on the 12V line, which is what
those cards use. So I run each card off its own supply.
But the 12V line at no load, or even at 300W, is only
giving out 10 to 10.5V. If I attach a small dummy load of
an amp or so to the 5V line, the 12V line suddenly becomes
12V.

Why are the two lines related in any way?

they are all on the same transformer so they are related,
and the feedback is a combination of 12V and 5V

Not sure how a shared transformer can work. Since I can
draw for example 5 times as much current from one line so
the other would be adversely affected surely? They have to
adjust each individually or it would go completely out of
whack. I take more 5V current, so the whole thing gets
boosted, now 12V becomes 14V.


Time-averaged output voltage(s) of an e.g. ideal flyback
converter with either single or multiple secondaries in
continuous conduction mode is a function of the input
voltage, duty cycle, and turns ratio only it isn't directly
dependent on any currents.

That is to say in the non-ideal case with a heavy load on the
5V and a light load on the 12 the 12 will not go out of
regulation nearly that bad in a well-designed converter; the
duty cycle is not supposed to be swinging wildly over light
load to full load in CCM (until maybe it drops into DCM at
very light load.)

Sounds like a clever design which fails under certain
circumstances. Plenty folk have a computer with two or more
graphics cards, so they need a 2nd power supply. Nowhere does
it state the supply has to be loaded on the 5V line.

Yes it "fails" when they cheap out on everything else in the
supply, surely. How much you pay for them again?

Not regulating the 12V properly is cheaping out, and from what
I've read in these groups a lot of them are like that.

They're CIT supplies. They don't explode like Alpine when you
dare to use more than 50% of the rated current, but they're not
as stable as a proper Corsair.


Best PC PSUs I have used are by EVGA.

Those guys know how to make circuit boards and propely manage
what
is on them and where the juice is moving and what parts are
producing heat. Their MOBOs are pretty good too, thought the
gamingtard mobo makers have won out now due to so many gaming
dopes building their own machines. Once you get all that money
you can start doing better and better engineering in your
products. Look at AMD. They *might* beat out Intel for a bit,
but don't count out the big boys that got us all here yet.

I haven't seen much from EVGA. I got a graphics card from them
once and it was fine. They make other stuff then?

Motherboards, Graphics adapters, PSUs and a few other things.
They actually took Nvidia and did some cards which were fully
compliant wher other only had some of the elements. Look though their
cards, they had some of the best and the other guys followed, and now
all have high end cards with huge memoray arrays on them. EVGA was
among the earliest to make high end Nvidia offerings.
Click to expand...

Someone running the SETI project told me he has a 1600W EVGA power supply (for 7 watercooled graphics cards). Apparently it runs perfectly. I'd never even heard of a computer PSU over 1000W. I've always stuck to Corsair for supplies, but I'll be adding EVGA to that list.
 
On Thursday, 5 March 2020 23:45:03 UTC, Commander Kinsey wrote:
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

Someone running the SETI project told me he has a 1600W EVGA power supply
(for 7 watercooled graphics cards). Apparently it runs perfectly. I'd
never even heard of a computer PSU over 1000W. I've always stuck to
Corsair for supplies, but I'll be adding EVGA to that list.
Click to expand...

There are plenty of old HP server power supplies on eBay at very low prices.
They are all 12V at up to around 1.5kW and have built-in fans. The lower
power ratings are more common, for example 750W or 1.2kW. They all have a standard edge connector. Multiple identical PSUs can be connected in
parallel. Certain pins must be linked to turn them on - the info is out there.
I can post the part number of the mating connector if anyone is interested.
The connectors are available from Mouser.

John
 
On Fri, 06 Mar 2020 14:09:44 -0000, <jrwalliker@gmail.com> wrote:

On Thursday, 5 March 2020 23:45:03 UTC, Commander Kinsey wrote:
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

Someone running the SETI project told me he has a 1600W EVGA power supply
(for 7 watercooled graphics cards). Apparently it runs perfectly. I'd
never even heard of a computer PSU over 1000W. I've always stuck to
Corsair for supplies, but I'll be adding EVGA to that list.

There are plenty of old HP server power supplies on eBay at very low prices.
They are all 12V at up to around 1.5kW and have built-in fans. The lower
power ratings are more common, for example 750W or 1.2kW. They all have a standard edge connector. Multiple identical PSUs can be connected in
parallel. Certain pins must be linked to turn them on - the info is out there.
I can post the part number of the mating connector if anyone is interested.
The connectors are available from Mouser.
Click to expand...

Are they happy giving out only 12V? As in no load on the other voltage lines?

I didn't know older supplies would be that powerful. Wow, Ł17.50 for a 2450W including postage in the UK. I wish I'd seen that. I'm waiting on a 1000W supply from China....

Changing the connectors ain't a problem.

Are they really ok in parallel? If one is trying to give out 12.05V and the other 11.95V (even identical models will never be really identical), then surely only the first will supply any current, and will overload. Not that it matters with 2450W, I'd have several smaller loads so they can be split between supplies.
 
On Friday, 6 March 2020 19:41:16 UTC, Commander Kinsey wrote:
On Fri, 06 Mar 2020 14:09:44 -0000, <jrwalliker@gmail.com> wrote:

On Thursday, 5 March 2020 23:45:03 UTC, Commander Kinsey wrote:
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

Someone running the SETI project told me he has a 1600W EVGA power supply
(for 7 watercooled graphics cards). Apparently it runs perfectly. I'd
never even heard of a computer PSU over 1000W. I've always stuck to
Corsair for supplies, but I'll be adding EVGA to that list.

There are plenty of old HP server power supplies on eBay at very low prices.
They are all 12V at up to around 1.5kW and have built-in fans. The lower
power ratings are more common, for example 750W or 1.2kW. They all have a
standard edge connector. Multiple identical PSUs can be connected in
parallel. Certain pins must be linked to turn them on - the info is out
there.
I can post the part number of the mating connector if anyone is interested.
The connectors are available from Mouser.

Are they happy giving out only 12V? As in no load on the other voltage lines?
Click to expand...

Yes. They have low-power auxiliary outputs but these do not need to be loaded.

I didn't know older supplies would be that powerful. Wow, ÂŁ17.50 for a 2450W including postage in the UK. I wish I'd seen that. I'm waiting on a 1000W supply from China....

Changing the connectors ain't a problem.

Are they really ok in parallel? If one is trying to give out 12.05V and the other 11.95V (even identical models will never be really identical), then surely only the first will supply any current, and will overload. Not that it matters with 2450W, I'd have several smaller loads so they can be split between supplies.
Click to expand...

They are designed as redundant supplies, so they have a well-defined voltage
droop with increasing output current which guarantees sensible load sharing..
The only requirements are that all shared supplies must be the same output
power and efficiency rating. Make sure you get the newer designs which
include a cooling fan rather than relying on an external fan in the server.
Some have output current monitoring with analogue and i2c interfaces.
The 2450W ones on ebay look huge and I can't see from the pictures whether
they have a fan. Look for HP common slot power supplies. All my comments
relate to these.
This link might be useful as it seems to relate to the same or similar
supplies:
https://power.murata.com/pub/data/acdcsupplies/d1u86p-w-1600-12-hbxdc.pdf
and this:
http://colintd.blogspot.com/2016/10/datasheets-relating-directly-to-hp.html

John
 
On 7/3/20 7:51 pm, jrwalliker@gmail.com wrote:
On Friday, 6 March 2020 19:41:16 UTC, Commander Kinsey wrote:
On Fri, 06 Mar 2020 14:09:44 -0000, <jrwalliker@gmail.com> wrote:

On Thursday, 5 March 2020 23:45:03 UTC, Commander Kinsey wrote:
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

Someone running the SETI project told me he has a 1600W EVGA power supply
(for 7 watercooled graphics cards). Apparently it runs perfectly. I'd
never even heard of a computer PSU over 1000W. I've always stuck to
Corsair for supplies, but I'll be adding EVGA to that list.

There are plenty of old HP server power supplies on eBay at very low prices.
They are all 12V at up to around 1.5kW and have built-in fans. The lower
power ratings are more common, for example 750W or 1.2kW. They all have a
standard edge connector. Multiple identical PSUs can be connected in
parallel. Certain pins must be linked to turn them on - the info is out
there.
I can post the part number of the mating connector if anyone is interested.
The connectors are available from Mouser.

Are they happy giving out only 12V? As in no load on the other voltage lines?

Yes. They have low-power auxiliary outputs but these do not need to be loaded.

I didn't know older supplies would be that powerful. Wow, ÂŁ17.50 for a 2450W including postage in the UK. I wish I'd seen that. I'm waiting on a 1000W supply from China....

Changing the connectors ain't a problem.

Are they really ok in parallel? If one is trying to give out 12.05V and the other 11.95V (even identical models will never be really identical), then surely only the first will supply any current, and will overload. Not that it matters with 2450W, I'd have several smaller loads so they can be split between supplies.

They are designed as redundant supplies,
Click to expand...

Any possibility of lifting one of them from ground so two could be
series-connected to produce 24V?

CH
 
On Monday, 9 March 2020 03:29:56 UTC, Clifford Heath wrote:
On 7/3/20 7:51 pm, jrwalliker@gmail.com wrote:
On Friday, 6 March 2020 19:41:16 UTC, Commander Kinsey wrote:
On Fri, 06 Mar 2020 14:09:44 -0000, <jrwalliker@gmail.com> wrote:

On Thursday, 5 March 2020 23:45:03 UTC, Commander Kinsey wrote:
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

Someone running the SETI project told me he has a 1600W EVGA power supply
(for 7 watercooled graphics cards). Apparently it runs perfectly. I'd
never even heard of a computer PSU over 1000W. I've always stuck to
Corsair for supplies, but I'll be adding EVGA to that list.

There are plenty of old HP server power supplies on eBay at very low prices.
They are all 12V at up to around 1.5kW and have built-in fans. The lower
power ratings are more common, for example 750W or 1.2kW. They all have a
standard edge connector. Multiple identical PSUs can be connected in
parallel. Certain pins must be linked to turn them on - the info is out
there.
I can post the part number of the mating connector if anyone is interested.
The connectors are available from Mouser.

Are they happy giving out only 12V? As in no load on the other voltage lines?

Yes. They have low-power auxiliary outputs but these do not need to be loaded.

I didn't know older supplies would be that powerful. Wow, ÂŁ17.50 for a 2450W including postage in the UK. I wish I'd seen that. I'm waiting on a 1000W supply from China....

Changing the connectors ain't a problem.

Are they really ok in parallel? If one is trying to give out 12.05V and the other 11.95V (even identical models will never be really identical), then surely only the first will supply any current, and will overload. Not that it matters with 2450W, I'd have several smaller loads so they can be split between supplies.

They are designed as redundant supplies,

Any possibility of lifting one of them from ground so two could be
series-connected to produce 24V?

CH
Click to expand...

I looked into doing this, but haven't tried it yet. One option is to
disconnect the mains earth from the upper one and let the case sit at +12V.
This will work, but has obvious dangers. Alternatively, the case can be
disconnected from the negative output internally. I have seen pictures
of such mods on HP common rail PSUs.

It would be wise to connect a very large reverse biased schottky diode
or equivalent across the output of each one to minimise the risk of
damage from reverse voltage if they switch on or off at different rates.

John
 
On Monday, 9 March 2020 10:12:40 UTC, jrwal...@gmail.com wrote:
On Monday, 9 March 2020 03:29:56 UTC, Clifford Heath wrote:
On 7/3/20 7:51 pm, jrwalliker@gmail.com wrote:
On Friday, 6 March 2020 19:41:16 UTC, Commander Kinsey wrote:
On Fri, 06 Mar 2020 14:09:44 -0000, <jrwalliker@gmail.com> wrote:

On Thursday, 5 March 2020 23:45:03 UTC, Commander Kinsey wrote:
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

Someone running the SETI project told me he has a 1600W EVGA power supply
(for 7 watercooled graphics cards). Apparently it runs perfectly. I'd
never even heard of a computer PSU over 1000W. I've always stuck to
Corsair for supplies, but I'll be adding EVGA to that list.

There are plenty of old HP server power supplies on eBay at very low prices.
They are all 12V at up to around 1.5kW and have built-in fans. The lower
power ratings are more common, for example 750W or 1.2kW. They all have a
standard edge connector. Multiple identical PSUs can be connected in
parallel. Certain pins must be linked to turn them on - the info is out
there.
I can post the part number of the mating connector if anyone is interested.
The connectors are available from Mouser.

Are they happy giving out only 12V? As in no load on the other voltage lines?

Yes. They have low-power auxiliary outputs but these do not need to be loaded.

I didn't know older supplies would be that powerful. Wow, ÂŁ17.50 for a 2450W including postage in the UK. I wish I'd seen that. I'm waiting on a 1000W supply from China....

Changing the connectors ain't a problem.

Are they really ok in parallel? If one is trying to give out 12.05V and the other 11.95V (even identical models will never be really identical), then surely only the first will supply any current, and will overload. Not that it matters with 2450W, I'd have several smaller loads so they can be split between supplies.

They are designed as redundant supplies,

Any possibility of lifting one of them from ground so two could be
series-connected to produce 24V?

CH

I looked into doing this, but haven't tried it yet. One option is to
disconnect the mains earth from the upper one and let the case sit at +12V.
This will work, but has obvious dangers. Alternatively, the case can be
disconnected from the negative output internally. I have seen pictures
of such mods on HP common rail PSUs.

It would be wise to connect a very large reverse biased schottky diode
or equivalent across the output of each one to minimise the risk of
damage from reverse voltage if they switch on or off at different rates.

John
Click to expand...

Common slot, not common rail!
 
On 2/20/2020 4:16 PM, Commander Kinsey wrote:
Why do (cheap? expensive ones may be better) PC ATX power supplies need
current drawn from the 5V line to make the 12V line work correctly?

I have a PC with 3 graphics cards running scientific applications.  I
acquired three old graphics cards that take about 300W each, and have
loads of cheap (CIT) PSUs that are rated at 650W on the 12V line, which
is what those cards use.  So I run each card off its own supply.  But
the 12V line at no load, or even at 300W, is only giving out 10 to
10.5V.  If I attach a small dummy load of an amp or so to the 5V line,
the 12V line suddenly becomes 12V.

Why are the two lines related in any way?
Click to expand...

This looks handy!
https://www.mpja.com/03-09-20.asp?r=291490&s=7
Mikek
Click to expand...
 
On 3/9/2020 9:55 AM, Michael Terrell wrote:
On Monday, March 9, 2020 at 10:26:08 AM UTC-4, amdx wrote:
On 2/20/2020 4:16 PM, Commander Kinsey wrote:
Why do (cheap? expensive ones may be better) PC ATX power supplies need
current drawn from the 5V line to make the 12V line work correctly?

I have a PC with 3 graphics cards running scientific applications.  I
acquired three old graphics cards that take about 300W each, and have
loads of cheap (CIT) PSUs that are rated at 650W on the 12V line, which
is what those cards use.  So I run each card off its own supply.  But
the 12V line at no load, or even at 300W, is only giving out 10 to
10.5V.  If I attach a small dummy load of an amp or so to the 5V line,
the 12V line suddenly becomes 12V.

Why are the two lines related in any way?

This looks handy!
https://www.mpja.com/03-09-20.asp?r=291490&s=7
Mikek


One review said those are not banana jacks. Just cheap binding posts to wrap wire around.
Click to expand...

Well that does suck! If I were interested, I have a drawer with plenty
of banana connectors I could do a replacement.

Mikek
 
On Monday, March 9, 2020 at 10:26:08 AM UTC-4, amdx wrote:
On 2/20/2020 4:16 PM, Commander Kinsey wrote:
Why do (cheap? expensive ones may be better) PC ATX power supplies need
current drawn from the 5V line to make the 12V line work correctly?

I have a PC with 3 graphics cards running scientific applications.  I
acquired three old graphics cards that take about 300W each, and have
loads of cheap (CIT) PSUs that are rated at 650W on the 12V line, which
is what those cards use.  So I run each card off its own supply.  But
the 12V line at no load, or even at 300W, is only giving out 10 to
10.5V.  If I attach a small dummy load of an amp or so to the 5V line,
the 12V line suddenly becomes 12V.

Why are the two lines related in any way?

This looks handy!
https://www.mpja.com/03-09-20.asp?r=291490&s=7
Mikek
Click to expand...

One review said those are not banana jacks. Just cheap binding posts to wrap wire around.
 
On Monday, March 9, 2020 at 11:27:41 AM UTC-4, amdx wrote:
On 3/9/2020 9:55 AM, Michael Terrell wrote:
On Monday, March 9, 2020 at 10:26:08 AM UTC-4, amdx wrote:
On 2/20/2020 4:16 PM, Commander Kinsey wrote:
Why do (cheap? expensive ones may be better) PC ATX power supplies need
current drawn from the 5V line to make the 12V line work correctly?

I have a PC with 3 graphics cards running scientific applications.  I
acquired three old graphics cards that take about 300W each, and have
loads of cheap (CIT) PSUs that are rated at 650W on the 12V line, which
is what those cards use.  So I run each card off its own supply.  But
the 12V line at no load, or even at 300W, is only giving out 10 to
10.5V.  If I attach a small dummy load of an amp or so to the 5V line,
the 12V line suddenly becomes 12V.

Why are the two lines related in any way?

This looks handy!
https://www.mpja.com/03-09-20.asp?r=291490&s=7
Mikek


One review said those are not banana jacks. Just cheap binding posts to wrap wire around.


Well that does suck! If I were interested, I have a drawer with plenty
of banana connectors I could do a replacement.
Click to expand...

I have a few hundred of various styles, to replace worn out ones on test equipment. I just wanted to point it out, before someone bought one, then they had to order real combo binding posts/banana jacks.
 
On Mon, 09 Mar 2020 10:12:34 -0000, <jrwalliker@gmail.com> wrote:

On Monday, 9 March 2020 03:29:56 UTC, Clifford Heath wrote:
On 7/3/20 7:51 pm, jrwalliker@gmail.com wrote:
On Friday, 6 March 2020 19:41:16 UTC, Commander Kinsey wrote:
On Fri, 06 Mar 2020 14:09:44 -0000, <jrwalliker@gmail.com> wrote:

On Thursday, 5 March 2020 23:45:03 UTC, Commander Kinsey wrote:
On Tue, 25 Feb 2020 01:56:55 -0000, <DecadentLinuxUserNumeroUno@decadence.org> wrote:

Someone running the SETI project told me he has a 1600W EVGA power supply
(for 7 watercooled graphics cards). Apparently it runs perfectly. I'd
never even heard of a computer PSU over 1000W. I've always stuck to
Corsair for supplies, but I'll be adding EVGA to that list.

There are plenty of old HP server power supplies on eBay at very low prices.
They are all 12V at up to around 1.5kW and have built-in fans. The lower
power ratings are more common, for example 750W or 1.2kW. They all have a
standard edge connector. Multiple identical PSUs can be connected in
parallel. Certain pins must be linked to turn them on - the info is out
there.
I can post the part number of the mating connector if anyone is interested.
The connectors are available from Mouser.

Are they happy giving out only 12V? As in no load on the other voltage lines?

Yes. They have low-power auxiliary outputs but these do not need to be loaded.

I didn't know older supplies would be that powerful. Wow, Ł17.50 for a 2450W including postage in the UK. I wish I'd seen that. I'm waiting on a 1000W supply from China....

Changing the connectors ain't a problem.

Are they really ok in parallel? If one is trying to give out 12.05V and the other 11.95V (even identical models will never be really identical), then surely only the first will supply any current, and will overload. Not that it matters with 2450W, I'd have several smaller loads so they can be split between supplies.

They are designed as redundant supplies,

Any possibility of lifting one of them from ground so two could be
series-connected to produce 24V?

CH

I looked into doing this, but haven't tried it yet. One option is to
disconnect the mains earth from the upper one and let the case sit at +12V.
This will work, but has obvious dangers.
Click to expand...

Pah, earths aren't all they're cracked up to be. In fact I've taken the earth off my microwave as my pet sits on it and chews wires. No ground, no circuit.
 
On Mon, 09 Mar 2020 14:26:08 -0000, amdx <nojunk@knology.net> wrote:

On 2/20/2020 4:16 PM, Commander Kinsey wrote:
Why do (cheap? expensive ones may be better) PC ATX power supplies need
current drawn from the 5V line to make the 12V line work correctly?

I have a PC with 3 graphics cards running scientific applications. I
acquired three old graphics cards that take about 300W each, and have
loads of cheap (CIT) PSUs that are rated at 650W on the 12V line, which
is what those cards use. So I run each card off its own supply. But
the 12V line at no load, or even at 300W, is only giving out 10 to
10.5V. If I attach a small dummy load of an amp or so to the 5V line,
the 12V line suddenly becomes 12V.

Why are the two lines related in any way?

This looks handy!
https://www.mpja.com/03-09-20.asp?r=291490&s=7
Click to expand...

What is it with California?

"WARNING: This product can expose you to chemicals including Nickel which is known to the State of California to cause cancer and which is known to the State of California to cause birth defects and/or other reproductive harm."
 
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