Mobo: ASUS Rampage II
CPU: Core i7 940
RAM: 6GB OCZ DDR3
GPU: Galaxy GeForce 470
PSU: OCZ 1,010 watt
OS: Win 7 64-bit
No overclocking (at least at the time of the crash)
Aftermarket cooling for the CPU (CPU stays within 40-50 degree C range depending on load)
Now, for the problem I am experiencing...
I was playing Civ V last night when my computer just abruptly turned off, as if it has lost power (but there was no power outtage). Of course I was confused (my 1st thought being, oh damn, my power supply just died), so I took a quick glance at my case and noticed that the lights that are on the motherboard (i.e. the light-up power/reset and bios control buttons and general status light) were still on like normal.
So I tried to turn my computer back on, but it would not respond to the On switch. I tried the switch on my case, then tried the Power button on the mobo itself, neither of which would turn the computer back on.
I flipped the power switch, on the PSU, to off and then back on and gave it another try and after pressing the power switch a few times, the computer finally responded and began to boot up.
The computer booted fine, without any errors or messages, other than "Windows did not shutdown correctly", and Windows 7 started up just fine too.
I jumped back into the game and not but a few minutes in, the computer cut off again.
It didn't take as long to get back on, but the third time it turned off on me (while just in Windows, not in a game), it took probably 10 minutes before I could get it to turn on.
The last time it shutdown on me, I was in the BIOS checking to see if there was an 'overheating' protection setting that was turning my computer off. I wasn't able to find anything, so I did a Save & Exit and as soon as I hit Enter, the computer completely shut off.
Now, the lights that are on the mobo are blinking on and off, as if the power to the PSU is being turned on and off.
It seems like the most likely causes would be either the PSU or the motherboard, but I am hoping to get some input from others. I would like to know what you guys think.
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. At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.
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.