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Signs of a fried cpu

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May 19, 2011 7:56:09 PM

Hello,I would like to know the answer to this annoying problem.2Wks ago my pc just turned itself off & would not turn on again,the only way i could start my pc was to disconnect the 4pin atx pwr to my cpu.What in the world happened to my PC?

More about : signs fried cpu

a c 78 à CPUs
May 19, 2011 8:07:45 PM

I would first look at your PSU and test with another PSU to see how it performs...
Anonymous
a b à CPUs
May 19, 2011 8:49:54 PM

This topic has been moved from the section Forum Feedback to section CPU & Components by Grumpy9117
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May 19, 2011 10:02:54 PM

That's been done twice & it does the same thing.I've even tried another motherboard,& still the same thing.What else could it be?
a b à CPUs
May 19, 2011 10:12:54 PM

CPU could be fried, you have eliminated motherboard and PSU right? The only way to be sure is to take the CPU to a computer shop and have them stick it in another mobo, just to be sure. RAM, may or may not be an issue. But I doubt it, as it would cause the puter to not boot, and weird too.
May 20, 2011 12:38:13 AM

If it makes no noise at all when the 4 pin CPU power is plugged in, but it tries to boot when you unplug it (of course, it still wont boot, but it will make noise), then you probably have a MOSFET/VRM failure (that is, dead motherboard)...
a c 172 à CPUs
May 20, 2011 3:11:13 PM

Time for some serious troubleshooting ...

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. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:
http://www.cwc-group.com/casp.html

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.

Motherboard LED's mean very little. When on, all they are telling you is that the computer is plugged into a live power socket and the PSU is switched on by its back panel switch.

Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
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.
June 11, 2011 4:43:29 PM

Did everything listed on your reply jsc & it happened. A little do-hicky thingy popped & gave acute lite show but an ugly smell. So i now know i know it was the mama board.thanks for your help.
!