Computer starts then reboots after 5 seconds

[c0nfUsi0n]

Hey guys, I just put a new computer together about a week ago and got it working right. But now my system crashed, and when i go to start it up, it just reboots after about 5 seconds, and it repeats over and over. I eventually took everything out and left just the mobo, psu, and cpu in there and it does the same thing. The only time i can get it to start up is when i unplug the ATX 12v power connector. I have a feeling i need a new motherboard but i just wanted to make sure. My power supply has both a 4 pin connector and an 8 pin connector but it still does the same thing whether i use either of them. I even tried an old 500W psu to see if it would make a difference, but it didnt.

motherboard: ASROCK K10N780SLIX3-WiFi
CPU: AMD Phenom 9950 2.6G Quad-Core

 

[c0nfUsi0n]

oh an also, i tried it without the cpu and it stayed running for longer than 5 seconds.

 

[major53]

c0nfUsi0n have tried unplugging the cmos battery on the mobo for about 3 to 5 minutes.you will have to go back into bios and reset date and time.

also could pull out and try 1 stick of ram.

we know your mobo and cpu but the rest of the spec would help people to come in and help you.

 

[c0nfUsi0n]

well i've tried the cmos thing and it didnt make any difference,. Ive tried it with no ram installed at all, and it still did the reboot cycle.

oh and i completely forgot to mention this before, but i was updating my BIOS and my computer froze, so i went to restart and thats what really started it

 

[pent5ht]

Your BIOS has most likely been corrupted, Remove the Battery for 6-8 hours overnight, that's how long it will take to drain all the power and try to reboot, you will probably need a new motherboard.

 

[c0nfUsi0n]

just tried that, no luck

 

[major53]

well i've tried the cmos thing and it didnt make any difference,. Ive tried it with no ram installed at all, and it still did the reboot cycle.

oh and i completely forgot to mention this before, but i was updating my BIOS and my computer froze, so i went to restart and thats what really started it

c0nfUsi0n now this makes more sense how did you try to flash the bios through windows,or jump drive or floppy.what happen to you is when you restarted while it was flashing the bios is it screwed up the eprom on the motherboard,I also had this to happen to me and I was able to reflash the bios to get it to work,and yes it's hard to straightened out but it can be done.I used a jump drive to fix it after I got into the bios,so first can you get to the bios.