New computer was working, and now it's broken

[nombrecinq]

This is a recent build:

AMD64 3200+ 2.0GHz single core
DFI Ultra-D LanParty non-SLI
Seasonic 600w power supply
2 320GB Western Digital hard drives in RAID mirror
ATI x800xl 256MB video card
2GB OCZ 3200 RAM 2x1GB
Antec P180
Linksys 802.11g WiFi PCI card

For a few months the computer has been ultra reliable. The first hiccups were that it would occasionally start up but the fans would not slow down and the computer wouldn't start. When it works the fans will go full steam at the beginning and then slow down to normal. Also occasionally the computer wouldn't start, but unplugging the PSU and re-plugging it in helped sometimes, and just repeatedly pushing the start button really hard would make it start if you got lucky.

Last night I installed Meetro which is an IM client. That killed my WiFi connection and I couldn't get it back. I went into "network connections" and it only showed the wired LAN connection I have to a router. So I restarted the computer. That didn't fix the problem so I shut it down for a while. Then the computer wouldn't start, and playing with connections would once in a while get it to start, but just fans at full blast.

The next thing I did was take EVERYTHING out of the case. I set up only the core components on my desk without a case to test; just the motherboard/proc/RAM/etc, power supply, hard drive cage, video card. The first time plugging everything in the computer started and booted, but the boot priority needed fixing in the bios because I had hard drives plugged into different SATA slots. I restarted and it didn't work. The power button on the motherboard wouldn't make it start again.

Has anybody run into problems like this and does it sound like it's definitely the motherboard, or definitely the power supply, etc? Please help I have so much stuff on those hard drives and I need to get this computer up and running for work! Thanks,

Scott

 

[YahoKa]

Strongly suggest checking the power supply first. Take a digtal multimeter, and check the voltage on each rail, and make sure it is within ATX tolerance. That's where I always start, and rather surprisingly, it often is the problem when it isn't immediately obviously a single component, or the problem comes and goes with no explanation.

 

[nombrecinq]

So I just need to get a 12V PSU tester from a CompUSA or something? Will it come with all the necessary instructions for how to test each rail?

 

[YahoKa]

If you have a voltmeter lying around, you can do it yourself without buying anything. If you can get the computer to boot ok, then turn it on, go to the BIOS, grab one of the molex connectors and check the Yellow to Black and Red to Black connections. If those are ok, you can try checking the mainbord connection (unplug everything from the PSU, short pin 14 to ground, and then check the voltages, check out this diagram www.duxcw.com/faq/ps/ps4.htm). If you're not comfortable doing this, don't. I don't want to be blamed for anyone's death.

 

[nombrecinq]

I don't mind buying a $15 PSU tester so that's not a problem. I hope it's the PSU that's the problem because that's the easiest thing to replace. Also I'm ditching the Antec P180 because there's not enough room to do anything in there. I had to take everything out to test things because with the PSU wires it's just too cluttered.

 

[nombrecinq]

After work I went to CompUSA to buy a power supply tester, and here are the results. When I plug in the 24 pin ATX connector, apparently all 7 lights are supposed to light up:

+5V
+12V
+3.3V
-5V
-12V
+5VSB
PG

Well they all light up EXCEPT -5V. When I plug the 24 pin cable, the P4 connector, and a molex cable into the extra space on the motherboard, and then press "power" ... it tries to start up but then isn't able to. The PSU fan seems to spin continuously while the 24 pin is connected to the tester, but can only run for a second when plugged into the motherboard.

Luckily I have this old P3 1GHz lying around which is what I'm using now, so I tried plugging that 20 pin connector into the PSU tester. All 7 lights light up.

So is the problem I've been having very likely 100% PSU, or could the motherboard be a factor? Also could somebody please explain what's going on?