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PC won't boot/post, fans spin...etc though

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December 11, 2010 12:34:47 AM

My PC won't post anymore(does not boot up). The fans power on and I can open/close the CD drive, but there's nothing on screen. I've tried 2 different motherboards, 2 different power supplies. I have no way to test the power supplies at this moment and one motherboard is brand new. The power supply's are a bit old and weak though, so I suspect it might be them, but everything does light up and spin, so that has me confused.

Also, I have tried onboard and pci-e video...no luck. Tried one ram stick at a time, no luck either. No beeps of any kind.

Could it be that my CPU is dead/burned/shot? Or probably just a power supply problem?


Motherboard: ASRock G31M-S
CPU: Intel E5200
GPU: Onboard and Nvidia 8600 PCI-E
PSU: Lite-On PS-6301-08A (300W), Other is 250 watt, lite-on also, bit older(both are old and pulled from old systems)
Ram: 2x1gb Crucial Ballistix DDR2 6400 memory

Rest of PC is just sata HDD and DVD drive.

More about : boot post fans spin

a b à CPUs
a b ) Power supply
December 11, 2010 12:56:59 AM

PSU might not be powerful enough for the system. Will need something at least 500W to make sure that is not the issue.
After switching these mobos around, did you re-apply the thermal paste on the CPU properly? I.e., cleaning CPU up with alcohol pads every time and then re-applying the paste?
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December 11, 2010 1:00:41 AM

Yep. Put some new AS5 on after wiping it pretty well. I did notice on the fan/heatsink...there looked like burn marks or something....but it could've just been "rotten" arctic silver. But it went away easily as I wiped it... That's why I wonder if it's a bad CPU...
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a b à CPUs
a b ) Power supply
December 11, 2010 1:10:55 AM

I would get a better PSU and try again. Another alternative would be to take the CPU and test it on a different PC. These steps should help troubleshooting it.
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December 11, 2010 2:33:14 AM

Thanks, that'll at least help me figure out what I need to replace.
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a c 172 à CPUs
a c 144 ) Power supply
December 11, 2010 3:11:06 PM

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

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: 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.

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 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.
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