A couple of years ago I built a gaming PC with a Q6600 CPU, an 8800GT 512MB graphics card, 4GBs of RAM, a Gigabyte GA-P35-DS3L motherboard, and a shitton of hard drive space for the time. I've since stopped gaming (mostly).
Recently, my primary use for my PC's horsepower was to transcode my entire DVD library to create a digital library. I've been running this thing for hours at a time, using Handbrake to transcode my movies into both a DVD-quality 480p format and also into an iPhone-compatible format.
Anyway, last night I ripped a bunch of my DVDs and set Handbrake to run basically all night, so that when I woke up in the morning, I'd have the entire Doctor Who series ready to import into iTunes. Instead, I woke up this morning to a blank screen.
So here's the symptoms, and what I've done so far:
- I power on the computer, but the screen doesn't even show POST.
- I changed monitors, in case it was the monitor
- I reset the CMOS
- I reseated the RAM
And, that's about it. I've only been troubleshooting for about 1.5 hrs. Tomorrow, I'll probably buy a PSU tester and test the power supply, but I wanted to get everyone else's input first on what might be the cause of this.
Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.
Make sure you plug the CPU power cable in. The system will not boot without it.
I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.
You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.
If no beeps: Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.
At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.
The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.
A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU.
This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.
If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.
Silence or long single beeps indicate a problem with the memory.
Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
I'm going to pass by Fry's today and see if I can get a PSU tester and a system speaker, but my suspicion is that I burnt out the CPU, because I was doing heavy (HEAVY) video transcoding at the time of failure, and I pulled out the hard drive and saw that it had stopped about two hours after starting the transcoding. And if I remember correctly (it's been a couple of years), I had overclocked my CPU a little bit.
Ok, this is what happened:
I bought a power supply tester (Coolmax PC-228), and I plugged in my PSU's 20-pin connector, flipped the switch on my power supply, and pressed the on/off button on the tester.
Well, not *nothing*. The LED glowed blue for about half a second, then died. Afterwards, it won't come back on again until I leave the PSU off for about a minute or so. Then, after a minute or two, I plug it back into the tester, turn the PSU on, and it repeats: short glow on the LED with some numbers (or letters), and then it dies.
What PSU do you have? If it's a 20-pin it must be rather old. I suggest you get a new PSU, even if it is not the source of your current problem, though the results of the PSU tester seem to indicate the PSU is bad.