Bad mobo or PSU?

[j_elbers32]

The last few days my computer generally won't even POST. I say "generally" because it has booted a couple times, but twice it froze (once while browsing the internet, once while gaming), and only once was I able to browse, game, do all that and shut it down normally.

It started after I left the computer on over a weekend while I was gone (was running BOINC). I came back after the weekend and it was frozen, so I restarted, but it wouldn't POST. I stripped all unnecessary components off of the mobo, down to the CPU and one stick of RAM, which didn't help. So I reseated my CPU and cooler, reset the CMOS, tried it, and it worked. I start putting components back in, eventually getting everything back in, computer boots, works for a half hour, then freezes, and won't POST again.

This morning when I tried starting it and it wouldn't POST, all I did was reset the CMOS, and it worked for 2-3 hours, then froze while watching Netflix. I tried resetting the CMOS again, but it didn't work this time.

Now, when I say that it won't POST, I mean when I power it on, all the fans come on, my hard drive spins up, CPU cooler fan comes on, mobo LEDs light up, etc.

The one time it's worked for an extended period of time (6-7 hours), I noticed the +12V reading was 11.68V, while it used to be ~12.1V. Granted, this was through CPUID, and software isn't always reliable, but it seems the change in values is more significant than the values themselves (still within tolerances).

I'm leaning most toward a mobo issue (hence why I posted it here instead of the PSU forum), since I assume a faulty PSU wouldn't work intermittently. I don't have any spare parts to swap in and out, either.

Specs:
Mobo: ASUS M4A89GTD Pro/USB 3
CPU: AMD Phenom II 965BE
PSU: Antec 650W TruePower New TP-650
GPU: SAPPHIRE Radeon HD 6850 1GB
Cooler: COOLER MASTER Hyper TX3 RR-910-HTX3-G1
RAM: 4x2GB G.SKILL Ripjaws CL7 1333 DDR3
SSD: OCZ Vertex 2 90GB
HDD: Samsung Spinpoint F3 1TB
OS: Win7 64-bit

Any help would be appreciated!

 

[nikorr]

When u start, is the PSU going on every time?

 

[robertnewton]

It doesn't sound like a power supply problem. Sounds like a problem with the CPU, RAM, or motherboard. Have you tried using each of your ram individually alone in different spots? Run a system diagnostics if you can

 

[j_elbers32]

The fan has come on every time I've checked, yes. It's been on both when the computer has worked, and when the computer hasn't worked.

 

[j_elbers32]

I've tried one stick of RAM individually, when I stripped everything down. Other than that, I've been using a pair in different spots (always in the 1st and 3rd, or 2nd and 4th slots, as normal).

And it hasn't worked after switching out the RAM alone. The DRAM LED won't come on at all when the computer doesn't work, but will come on for ~2 seconds then go off (which I recall being normal?) when the computer does work.

edit: I'll try individual sticks of RAM, just to be thorough.

 

[j_elbers32]

Ok, so I've tried a few individual sticks of RAM. Got one to work (in the 3rd RAM slot, I was thinking maybe one of the slots is bad), ran MemTest86+, no errors. So, I replaced that stick with a different one (also in the 3rd RAM slot), passed MemTest, and a 3rd stick also passed.

So, I went to install the 3 sticks that worked fine individually (in the 2nd, 3rd, and 4th RAM slots), to no avail. No POST. Went back to one RAM stick that previously worked, kept it in the 3rd slot as before, and that didn't work either. None of them will get my computer to POST now.

I'm not exactly sure what this means, any thoughts?

 

[robertnewton]

I suppose it's too late to respond now but do you have any updates? That's an interesting problem you're dealing with. At first guess i'd say you clearly have some problems with you RAM slots, but then again it's really hard to say at this point

 

[j_elbers32]

Update: i breadboarded my setup, worked perfectly. Installed it back into my case, havent had a single issue since. So it was probably a short, maybe a screw that worked loose. But its fixed, thanks for all of your suggestions!