A Peculiar Problem

[monkier2]

A while ago my main desktop computer has been suffering a problem that I as of yet have been unable to diagnose.
When the computer is turned off, simply pressing the power switch yields no results; the computer will not boot. To boot, I must manually disconnect the power, then reconnect; the motherboard initiates its standard sequence which I interrupt by pressing the power switch while in this phase, before this sequence would normally finish with a return to the off state. (It is worth noting that the problem has sense progressed from this phase, and I now accompany the power button switch with opening the DVD drive. In this way, while powering on the computer will spit out the drive, then shut off with the drive open; on my next boot attempt of manually disrupting the power, after retracting the drive the computer boots)
It is also worth noting that the RAM is not the issue, as I swapped in some old RAM that I knew to be okay. I unfortunately do not have many spare parts, such as motherboards or power supplies to test.

So, my question is, what course of action should I take next? Finances are tight, so I cant really afford to buy a bunch of parts for troubleshooting and would instead like to isolate the problem. It strikes me that it probably lies in the power supply, the motherboard, or possibly (?) the bios.

What do you all think?

Much thanks in advance!

My Specs:
CPU - AMD Athlon 64 X2 4600+
Hard Drive - Western Digital Caviar SE16 320GB SATA
GPU - BFG GeForce 7950GT (256MB RAM)
DVD Drive - Samsung SH-S182D/BEBE
PSU - Thermaltake W0128RU Toughpower 650W Modularized Power Supply w/Active PFC
RAM - 2GB OCZ DDR2 800 Dual Channel RAM; CAS Latency: 4
Motherboard - eVGA 122-M2-NF59-TR (590SLI)
OS - Windows XP Pro SP 2

 

[krnmastersgt]

How old is the motherboard? Might want to consider replacing the CMOS battery, although that usually doesn't have the ability to prevent an entire system from starting up, but it's a few dollars at your local drug store, hopefully you can spare that. I'd agree with you on the likelihood of the PSU being the source of the problem, however the circumstances lead me to believe otherwise as well.

You can boot/run the system without any problems, and yet you can't always boot. If it were the PSU, you wouldn't be able to boot the system successfully all the time with the method you mentioned, PSU problem = random error, certain other components = systematic. Try booting the system with nothing but a video card, cpu, and 1 stick of ram in it. If you can successfully boot without using your aforementioned method, it is indeed a power issue, post back here and I'll try and get back to you, if not another member.

 

[monkier2]

All components are a year and a half old. I have not yet tried replacing the CMOS battery, but the method you suggested of unplugging all but the most basic components yielded the same result as before, i.e., that it refused to boot.

 

[krnmastersgt]

Hmm, there might be a faulty circuit on the motherboard that's completed with the DVD drive being used for whatever reason, quite odd. That, or the PSU isn't delivering enough power at the start-up which is a large spike in power usage iirc. Know anyone who has a system you could dismantle for a little while? An overpowered PSU would be best just to ensure that it is, or is not, the PSU that's the problem. Otherwise it looks to be a faulty circuit in my eyes.

 

[monkier2]

Another update; I tried out my system with another power supply, borrowed from a friend for his new system build. The power supply itself is brand new, an OCZ 500W ModXstream I believe. This device gave the same result. I suppose this suggests that it is entirely the motherboard at fault then?