Computer continuously reboots a few seconds into POST

[Pollock]

Computer in signature (actually, using an Antec Trio 550W PSU at the moment) would randomly start slowing down, programs would become unresponsive, and eventually, the entire system would freeze. After several minutes it would BSOD and restart. This happened inconsistently but over a few months. I tested the RAM on memtest86 for 12 hours or so with no errors when this happened. It kept intermittently BSODing, but I was lazy and never figured it out/did anything about it (I deserve this).

Now the computer will continuously restart during POST - the LEDs, fans, etc. will power up for 5 seconds before turning off. After another 5-10 seconds it will start again and repeat this. So far I have tried booting it with a single stick of RAM in various slots, but no dice.

I think the motherboard is toast - do you guys concur? Should I just get a new one, RMA this one, and sell the RMAed board?

 

[sivart]

Try booting with the bare minimums and try to eliminate the point of failure. Probably a hardware problem, but I'd remove all the cards, disconnect the optical drives and see if I can get it to POST with just mobo, video, ram, cpu.

 

[llee]

Follow sivart's advice for the first half of the problem. The continually rebooting issue might be due to your case or screws shorting out a power connection though. Take apart the PC and start it with just the crucial components.

 

[mpilchfamily]

I would suggeat getting your hands on a system speaker and connecting it to the motehrboard. Chances are the board is throwing an error code before it restarts. This could help you figure out where the problem is at.

 

[Pollock]

I've swapped in a new EVGA P55 SLI motherboard, and the exact same situation occurs. I get post codes from the LED display of 62 and E8, which I think point to a memory issue (based on various forum posts)? At this point I have reduced it to just the CPU + HSF, 1 stick of ram in the first slot, video card (still sitting in the case though, and I don't have enough screws for all of the standoffs).

I don't see how the CPU could be damaged when I've barely tried to overclock it, and I know I haven't given it dangerous voltage. I've tried 4 different sticks of ram in this motherboard with the same result. What's happening?

 

[kprasad]

Looks like the SMPS powergood signal is weak. Check the orange cable voltage of your smps.
Or check the health of smps itself.

 

[Modelworks]

Do you know someone with a pci video card ? Must be pci not express. The reason is that motherboards that make it to the bios start stage will display output on a pci card. It is part of the motherboard bios spec. because they removed ISA slots and the feature was then moved to PCI. PCI cards are the very first device initialized after the POST and do not require the bios enter extended mode unlike express/AGP so the bios will display the output as soon as the pc is turned on as long as the bios can reach POST. If it doesn't display on a pci card, reset the CMOS jumper because usually a bios is set to look for something other than PCI if it detects one on boot. Remove all other cards as well.

Try to find the oldest, simple , basic pci card you can, not ones with overblown features like 512MB ram, just an old 8MB or 32MB card. High memory cards will likely not work because the memory is too large and gets remapped to extended mode like pci express.
They are on sites like ebay for $10 shipped. The old Trident cards with 1 or 2MB are perfect for this

 

[Pollock]

Here's a crazy one: the only unnecessary thing I had left to unplug was my front panel connectors (power, reset, etc), and since this new motherboard has power and reset buttons, I went ahead and unplugged them, not expecting anything different. It booted up successfully.

Ends up it reboots every 5 seconds if the reset button is plugged in to the pins - I'd never have thought of that. So right now I'm just running without the reset switch, but how could something like this prevent the system from booting?

 

[KGB]

Here's a crazy one: the only unnecessary thing I had left to unplug was my front panel connectors (power, reset, etc), and since this new motherboard has power and reset buttons, I went ahead and unplugged them, not expecting anything different. It booted up successfully.

Ends up it reboots every 5 seconds if the reset button is plugged in to the pins - I'd never have thought of that. So right now I'm just running without the reset switch, but how could something like this prevent the system from booting?

The switch is shorted.
The MB sees this the same as someone continuously pressing the reset button.