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Desktop Troubleshooting

Last response: in Motherboards
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October 22, 2011 3:24:41 AM

I've had an issue with my desktop for roughly the past two months. It won't turn on at all, the only sign of power is a solid green indicator light on the motherboard. I just received a replacement for it so that should turn out okay. I also just today tested my power supply, a Corsair TX750 to make sure it was running smoothly. It passed the paper clip test but I'm going to get a replacement from them just in case. Other than the motherboard and the power supply, what can be preventing my computer from turning on? The switches for the power button, reset, and HDD are set up correctly for sure but all the issues started to happen when I wanted to upgrade my computer and add a GTX 580 to it. It was a prebuilt computer, a Cyberpower PC Gamer Ultra GUA110, the case is http://azzatek.com/index.php?main_page=product_info&cPa... the motherboard is an M4N68T-M V2, video card is PNY GeForce GTX 580 Overclocked Enthusiast Edition, CPU is AMD Phenom II X4 855. The only issue I can think of is that the smaller side of the PCIe that my graphics card goes into, the graphics cards pins are shown very slightly. I'm not sure it would be a reason why it would cause all the problems the computer is having but any suggestions? Thanks in advance!
a b Ĉ ASUS
a c 156 V Motherboard
October 22, 2011 3:54:04 AM

The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

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 once you are finished.

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 (standby power supply): 5 volts always on. The green wire should also have 5 volts on it. It should go to 0 volts when you press the case power button, then back to 5 volts when you release the case power switch. 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.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

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. It is also an easy way to bypass a questionable case power switch.

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, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

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.

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October 22, 2011 4:08:41 AM

Thats the hard thing. There's no beeps, the motherboard LED isn't indicating any issues, its just a solid green, and no fans are spinning whatsoever. Makes it very difficult to diagnose.
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October 23, 2011 1:10:51 PM

Any suggestions?
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!