Can I safely disconnect auxiliary power from motherboard?

404zero · Post by **404zero** » Mon Sep 20, 2010 1:07 pm

Can the auxiliary power connector be safely disconnected from my motherboard without causing any problems?

I have a Dell GX520 mini tower that has noisy coil whine in the power supply unit, but only when the computer is off.

I'm guessing that it's the auxiliary power that keeps feeding power into the power supply when everything is turned off?

If it can be safely disconnected, would I just unplug the 12v 4-pin connector to disable auxiliary power?

Thanks!

dhanson865 · Post by **dhanson865** » Mon Sep 20, 2010 3:16 pm

no, that 4 pin power connector is to supply power to the CPU while the computer is on. Unplugging it will make the system unbootable most likely and unstable if it does boot OK.

Maybe someone else will jump in with a suggestion better than this but mine would be to plug the PC into a power strip and after shutting down the OS turn off the power strip. If you have a UPS just turn it off instead of using a strip.

washu · Post by **washu** » Mon Sep 20, 2010 3:16 pm

No, if your motherboard has a 4 pin 12v connector then it needs it. I don't know if anything will be damaged if you try to run with it disconnected, but your computer will most certainly not work. It supplies power to the CPU.

Also, that connector is not feeding power to the power supply, nothing is. The 5v standby line is drawing power from the supply at all times, but that is part of the main 20/24 pin ATX connector.

piglover · Post by **piglover** » Mon Sep 20, 2010 8:43 pm

Best case: your MB is well made and has over-current protection at the VRMs. In this case, the VRMs will just shut down, effectively powering off the CPU.

Worst case: the MB is poorly designed and just has all the 12v lines tied together. Since there is nothing protecting it, 12v power will flow from the 12v leads on the main 24 pin connector to the CPU VRMs - in which case you will see little puffs of smoke as the internal PC-board traces melt. You'll brick the MB, but all the removable components (memory, CPU, etc) should survive.

Not worth trying...

404zero · Post by **404zero** » Wed Sep 22, 2010 1:02 pm

So I guess my only option is to replace the power supply.

The question is, can I safely replace this BTX power supply with an ATX?

I've heard mixed opinions as to whether or not this can be done.

Thanks again!

piglover · Post by **piglover** » Wed Sep 22, 2010 1:43 pm

Safely replace BTX PSU with an ATX PSU? Of course - they are electrically identical and use identical connectors with identical cable layouts.

Can you physically do it? Depend entirely on the layout of your case and your skill/willingness to mod things (like make new screwholes, bend a little metal, etc). They aren't really that different. Be cautious that you don't block the fan or air vents on the PSU when it gets mounted.

Vicotnik · Post by **Vicotnik** » Wed Sep 22, 2010 2:22 pm

As dhanson865 already have pointed out, wouldn't something like a power strip with a switch solve the problem? Saves you a few watts as well.

In any case, I fail to see what the +12V 4pin connector has to do with this. The only active rail during standby is the +5VSB rail as far as I know.

Post by **MikeC** » Wed Oct 06, 2010 6:11 am

Consider what you have plugged (or not) into the USB ports when the system is off. USB devices often continue drawing power from the PSU's 5Vstandby line -- this could be the source of the problem. Try increasing the # of USB devices plugged in -- as well as decreasing.

If this is not the issue, then the power strip off/on is the best solution.

Reachable · Post by **Reachable** » Wed Oct 06, 2010 2:23 pm

Replacing the PSU on a Dell computer might be problematic. Dell is known for its use of proprietary parts that differ from the off-the-shelf parts used by other assemblers. A Dell computer that was new four years ago had a different pinout on the power connector on the motherboard. EndPCNoise used to sell an adapter -- I don't know whether they still do.

In any case, better solutions (unless you want to move to a quieter PSU) have been mentioned already.

alecmg · Post by **alecmg** » Fri Oct 08, 2010 12:50 am

external power switch is much simpler solution

I have PC, two monitors, speakers and printer and a battery charger on one power strip with a switch. Every ***** one of them draws 1-8 watts when "turned off". Makes ton of sense to completely power them down.

lm · Post by lm » Fri Oct 08, 2010 6:39 am

Its funny - there is a post by an obvious spammer immediately followed by a post from MikeC.

EDIT: This is no longer the case as evident from below.

quest_for_silence · Post by **quest_for_silence** » Fri Oct 08, 2010 7:30 am

lm wrote:Its funny - there is a post by an obvious spammer immediately followed by a post from MikeC.

Seemingly your message is not understandable, lm (nor seemingly in topic).

Post by **MikeC** » Fri Oct 08, 2010 7:40 am

quest_for_silence wrote:
lm wrote:Its funny - there is a post by an obvious spammer immediately followed by a post from MikeC.

Seemingly your message is not understandable, lm (nor seemingly in topic).

The spammer was deleted.