New PSU, powers on for <1 second then turns off

M Thompson

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Mar 26, 2013
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I've been using this setup for a while now, no issues. I recently just purchased a new GPU (Sapphire Nitro R9 390X) and after installing it, it didn't power up. I figured that this was because it needed x2 8 pin power and my PSU only provided x2 6 pin power.

So I ordered a new PSU (EVGA 120-G2-1000-XR 80 PLUS GOLD 1000 W) and plug everything in. When I press the power button, my case LEDs and fans all get power for less than a second before turning off. Repeated presses do nothing. I have to flip the PSU switch and wait a couple seconds and try again to see the same result. I did the paperclip test, and the PSU fans spin up just fine.

Now, I had read that there were compatibility issues between Gigabyte and EVGA so I ran out to the store and bough ANOTHER new power supply, this one was a 750w Corsair. After install, it does the exact same thing. Now I spent the past 2 days troubleshooting and trying to read up on the issue but nothing seems to work. I unplugged everything except the 24 pin mobo power and 8pin CPU power, all plugs are seated all the way, no pins are bent shorting out, checked the ram sockets 1 at a time. I even took the mobo out of the case in case the standoffs were shorting somehow. All with the same result of power for less than a second and then turning off.

My old Rocketfish PSU powers everything up just fine, which is how I'm writing this. So I don't think my mobo is dead, but at the same time I don't think both of those new PSUs are dead either. I'm at my wits end with this and need some help. I've read over just about every post I could find on this issue and nothing works.

Anyone have any ideas for me?

Current specs:
Gigabyte 990FXA-UD3 mobo
AMD FX-8350 cpu
32gb Corsair Ram
Sapphire Radeon HD 7950 gpu
 
It's unlikely the psu's fault.
It could be the ram or the motherboard itself.
Test a single module of ram and see if it boots.
If it still does not solve the problem, it could be a corrupt bios.

To recover from GIGABYTE Backup BIOS (Only for motherboards with Dual BIOS technology)

Method #1:

Shut off the power supply by pressing the button on the ”PSU” or by removing the power cable.
Press the power button 3-4 times to empty the stored energy in the power supply.
Turn on the power supply
Press and hold the power button, the system will start the bootup procedure but will shut down after a few second. Release the power button after the system have shut down completely.
Press the power button to start the system.
If this technique was successful the system will boot and you will see the following image.

Method #2:

Shut your PC down.
Hold the power AND the reset button for about 10 sec, than release.
Backup BIOS should kick in anytime soon now.

Method #3:

Short out pins 1 and 6 on the main BIOS chip (pin #1 should be marked with a red dot or whatever)
Tell a friend (or a relative) of yours to press the power on button
Remove the ghetto-like jumper you’re holding between pins 1 and 6 as soon as you hear a beep.
Backup BIOS should kick in again and everything will (hopefully) be fine.

Source:
http://www.gigabytenordic.com/gigabyte-tips-tricks-rma/
 

M Thompson

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Mar 26, 2013
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The Corsair psu is hardwired for the mobo and cpu power. The EVGA has the 24 pin broken into 2 plugs psu side, and cpu power is keyed differently if I remember right. Typically the 4+4 is the part that goes to the mobo anyway.
 

M Thompson

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Mar 26, 2013
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Can the bios really make something like this happen? And what would be the difference between an older and newer psu that would do it? I have seen the backup bios come up at one point after I put everything together but to no avail. Maybe I need to update it to the latest version. My version now is from 2013.
 

M Thompson

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Mar 26, 2013
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I updated my bios to the latest version for my mobo's rev (Rev.4), but the same issue is still happening. I'm starting to think I might just need a new motherboard.
 

M Thompson

Honorable
Mar 26, 2013
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So it turns out that my motherboard was somehow the issue here. I bought a new one (MSI 990FXA GAMING (MS-7893)) and my new PSU worked just fine with it.

I don't have a clue why the new PSU wouldn't work with my old motherboard when my old PSU worked with it fine, but at least the issue is solved for me.
 

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