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Is my CPU dead? 2 Motherboards down, still no video at all?

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September 19, 2010 11:00:22 PM

Hey everyone.

I have a strange problem.
My wife brought a tower back from the Philippines.
The power supply should be fine as it reads "SWITCHIG POWER SUPPLY" 230/115 on it.

The computer booted right in front of me over there, then windows died. Had some missing system file, and never booted again.

She packed it and shipped it over here.

I plugged it in. No video
Everything booted just fine in terms of fans, power supply etc. I heard the HDD spinning, but heard no beeping noise signaling post.

I tore down the system and rebuilt it.
Tried both ram sticks, then one, then none. Reseated the CPU, did all the regular troubleshooting stuff.
I looked up and saw that when people OVERCLOCK their computers with the MSI n1996 board that this happens, but that happens when their CPU becomes screwed.

I also reset the CMOS and BIOS via the battery removal and jumper switching as a last resort. No boot.

Today I went to Frys and bought a brand new never opened Gigabyte S-series motherboard...
Took apart the old components, carefully cleaned the CPU/HSF up and added new thermal paste etc, reassembled it and it STILL HAS NO VIDEO.

It powers up, but there is once again no audible sign of a post or boot. The HDD makes the faint noise that those quiet SATA drives make, but it just sits there with no signal going into the monitor.

I have tried 2 different monitors, with 2 different standard RGB monitor cables.

This board is using brand new kensington RAM, 2 banks of 1gb each.

So all in all, i am absolutely shaking my head at what this is all about, and i am at a total loss.
I just spend $120 today which thank God a large big box retailer will let me return with no fees, but i would love to get this to work.

Any ideas?
Thank you!
a c 899 à CPUs
a c 715 ) Power supply
September 20, 2010 1:23:24 AM

You are running on a IGP or discrete GPU? If it was the CPU it should not boot at all.
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a c 172 à CPUs
a c 144 ) Power supply
September 20, 2010 4:27:22 AM

If the system came from the Phillipines, it undoubtedly came with a POS PSU. I would first suspect the PSU.

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.

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...

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.
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September 20, 2010 3:31:52 PM

i should have pointed out instead of letting you waste all those words about the power supply (and i apologize) that i have two other PSUs here, and one of which is brand new 500w, which I tried out and would not boot board a (the original one that came with the system)

so since board a would not boot, i tried just the original PSU on the gigabyte new board, but later on i will check through the guide posted and post back here my results.
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September 20, 2010 11:20:21 PM

ok

went ahead and did all the stuff in the guide posted. ALL of it.
I went ahead and also bought a new 400w power supply as the one i had on hand was only 300w, and it still will not post.

i am at a loss. the cpu fan spins, thats all i know. you say that if the cpu was bad it wouldnt even boot though, so i dont know.
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September 21, 2010 1:46:29 AM

ok. the new board, new PSU now boots. i am now fighting windows to install.
i am remiss as to whether or not i should try and rebuild with the old MSI board and take the gigabyte back for the money i spent on it.
probably just keep things as they are, since it works and the board only cost like, $44 anyhow.
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a c 899 à CPUs
a c 715 ) Power supply
September 21, 2010 1:51:12 AM

It can be a bad hard drive, I guess you are about to find out if windows installs or not.
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September 21, 2010 3:30:09 AM

Well no matter what hdd it wouldn't boot. Using the 80gb sata now. Windows isn't installing, I'm burning a new copy of a disk i have when I get home as I hear getting stuck at expanding files is a common problem.
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