790FXT-UD5P won't boot, onboard LEDs blinking rapidly

[yugo23]

Yesterday when I shut down my computer I noticed that lights on my mouse and external hard drive are blinking rapidly, instead of solid light. Lights on power, reset and CMOS onboard buttons were also blinking rapidly. I tried unplugging from the outlet and plugging again, but that didn't help. I tried another power supply, without luck. Board just won't boot anymore. CMOS button is not working. Any ideas what I could do?

[Vezina]

Your old power supply may have killed the motherboard.
If CMOS clear doesn t fix it and you are sure that the new power supply is indeed 100% healthy ,you may need to RMA the mobo or buy a new one.
I recommend you quality PSU-s as a firecracker has the build-in ability to kill.
The stand-by voltage (the only one available when the PC is turned off) may have played a trick to the motherboard.

[yugo23]

I have Chieftec CFT-750, which is certainly not a bad power supply. I would be really surprised if it caused the problem. I took out battery from the motherboard before I went to work, I will see if that helps when I get home.

[Vezina]

I have Chieftec CFT-750, which is certainly not a bad power supply.

I agree ,but it s not impossible to go bad.
Test the power supply in another PC and see if it works.If it works properly then the board simply died.
I would also check for rootkits the hard drives ,maybe some virus killed the bios.

[yugo23]

Results of yesterday testing:

Removing battery didn't help. I didn't have another power supply with 8-pin CPU connector, but when I plugged just 24-pin connector from another PS LEDs were normal, I could boot, but obviously CPU fan was not spinning.
I tried the same with Chieftec, and I was also able to boot. Plugging 8-pin CPU connector was causing LEDs to blink fast, but after few disconnects I managed to get everything working and booted normally. That is, until I shut down my PC 6 hours later, when same blinking occured.

Obviously problem is with that 8-pin connector, either on power supply, or maybe power unit on the board is dying.

[Vezina]

Most probable the power connector contacts are loose or oxidated.
Take a look at both contacts in the mobo and PSU connector.
Try to tighten the ones on the PSU connector with some screw driver so they fit better.
Otherwise replace with another PSU or new connector on the cable ,as it can happen for those plastics to melt due to bad contact.