Press power button, Power supply and CPU fans power up, computer stays powered for 3 seconds, then both fans cut out and the capacitors/Converters in the power supply give the standard high pitch discharging sound simultaneously. The computer then automatically powers on 3 seconds later, and it cycles in this manner until power us cut at the supply. Hard drives still function - tested on a laptop through USB. There are no Beep codes.
Lightning storms - I was not home during the storm, but potentially could have struck outside the window where my computer is.
Unsuccessful Attempts at fixing:
-Removed hard drives, WIFI card, optical drive, USB devices, graphics card for all following testing. Boot tests done with power supply, RAM, CPU, and CPU fan installed.
-Removed all sinks, cleaned surfaces with alcohol, reapplied (just enough) conductive paste to surfaces
-Removed all RAM sticks but one, alternated which stick, tested different slots
-Tested the motherboard with both power supplies. The stock power supply was working last time it was used.
-Installed 6 digit QiGuan POST card - obtained readout 07F3no, unsure of what this actually means.
I've removed the board from the case for these tests, and made sure the rear of the board was not shorted, there are no loose screws to short anything, all the capacitors appear to be in good health, not buldging, not leaking, and there are none of the telltale black scorch marks from short circuits or over-voltage components.
Can anyone suggest anything else I should do? I don't even know where to begin in terms of testing individual components (I'll save re-flowing the hard drive as a last extreme attempt)
I'm inclined to start replacing components, but how do I determine whether it's the CPU that is bad or the Motherboard that is bad?
Cpus rarely go bad unless you were overclocking with extra voltage, or the heatsink came loose. You can't change motherboards if you want to reuse a factory windows installation, but you may have already upgraded to windows 7. Here's some ddr2 boards you can check out if you want to reuse your cpu and ram:
While I have never overclocked the CPU, I've lost a router and an NAS among other electrical equipment before due to proximity to lightning strikes even though they were grounded/surge protected. I thought perhaps the chip may have been affected by the strike? (don't know the first thing about what chips are actually made of.. besides a mess of transistors and semiconductors)
I don't care about re-using the factory windows installation, I can just use Linux or something (dare I say) better. I'll definitely take your advise and select one of those LGA775/DDR2 (64bit capable) boards, I just really wanted to make sure the problem lies within the motherboard first so i'm not wasting any money.