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CPU or mobo fried? Please help me determine

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November 8, 2010 7:16:54 PM

I have a home built computer, bit over a year old now, running asus p6t mobo and an i7-920, a 9600gso gpu, etc. All has been running fine except the temps have been a bit on the high side, and when I was running all 8 cores for CFD calculations, realtemp was saying that it was up around 90-100c. So obviously that is an issue, which means I've always had to only use 3/8 cores max to keep the temperature reasonable.

After some research I thought the heatsink (stock intel) might not be seated properly so I opened the case up and fidgeted around with that a bit but it seemed okay. I vacuumed the case out and went to turn the computer back on and to my dissapointment not much happened. Basically what happens is while the fans start up and the general "whir" of the computer is going, there is no power to any USBs or any communication with the monitor (I can't get into bios). As far as I can tell, there is no communication with the hard drive either - there's no clicking and the hd activity light remains blank. However, the motherboard power light and all fans are running, as well as the video card fan, etc. I've taken the video card out, two sticks of ram, unplugged both the optical and hard drive, and still have nothing. By nothing I mean there is no beep from the motherboard. I've also taken out all sticks of ram and tried to start up, because from what I understand the mobo should beep if there is no ram, but it did not. I think it is a cpu or motherboard that I've fried? Not sure how to diagnose the problem because I don't have extra i7 cpus, or i7 mobos just lying around...

Also, I have taken the cpu out and all the pins seem okay, I've cleaned the thermal paste off both the cpu and heatsink and am waiting for an aftermarket heatsink/paste to get here so I can put the cpu back in and fire it up. Could I have unseated the heatsink even more when I was messing with it, and then the cpu wouldn't fire up because of temperature reasons?

Also I think when I applied the thermal paste the first time I put too much on because when I cleaned it off it seemed too thick and that would help explain the weirdly high temperatures.

Any ideas on what I could do to figure out what is wrong? There is a microcenter near where I work so I could pick up another i7 tomorrow and try it... but I'm not sure what happens if it doesn't work - I don't really want to be stuck with an extra processor if i can help it. Could I return the cpu?

It is worth noting that there are no burn marks anywhere on the motherboard or cpu that I can tell. Everything looks to be inorder and I do get power to the mobo etc when I start up. I feel like it is the cpu, but I don't know whether or not I actually fried it, or if the heatsink was simply not properly attached and it won't turn on.

I really would appreciate any help you guys could give, I do have a multimeter so I can measure voltages if necessary though I kinda broke one of the tabs on my stock heatsink when I finally took it out to clean so that's another reason I'm waiting for the aftermarket one to try starting the computer... Therefore I can't turn the computer on until it gets here.

Worth noting: PSU is corsair 550w, real nice power supply... has had no issues and seems to be supplying power to all drives/fans etc. fine so I really do not think this is the problem.
November 8, 2010 7:32:58 PM

Seems simple enough to me,, take your cpu to the store and have them test it for you.??? :) 
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November 8, 2010 7:40:07 PM

Can you do that? Can I bring my computer to a microcenter and they will test...? I've never actually been to a microcenter but if it is anything like a best buy I don't want them touching my computer... heh.

Is there somewhere I could take it to have tested?
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a c 122 B Homebuilt system
November 8, 2010 7:55:29 PM

Before you tear everything down, try to do as much troubleshooting as you can.

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 beeps 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.

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.
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a b B Homebuilt system
November 8, 2010 8:04:32 PM

To be honest, that's a bit of a tricky one. Vacuuming a PC can create static, which in turn fries things. I'd put my money on your motherboard, CPUs are generally pretty tough... I've seen way more bad mobos than processors. I've also seen a lot of bad graphics cards...
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November 8, 2010 8:16:29 PM

(Vacuuming a PC can create static ) yes never vacuum !! this is why there is can air
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November 8, 2010 9:13:34 PM

jasonw223 said:
To be honest, that's a bit of a tricky one. Vacuuming a PC can create static, which in turn fries things. I'd put my money on your motherboard, CPUs are generally pretty tough... I've seen way more bad mobos than processors. I've also seen a lot of bad graphics cards...

I think I killed either the mobo or cpu by either vacuuming it or messing around with the heatsink.

Ugh, I would rather it be the cpu but do you think I could RMA the mobo if that is the issue?

My graphics card sucks, to be honest, and I initially thought it was that. It has been very loud lately, like the side of the fan is hitting the outer plastic ring around the fan. But I am 99% sure that is unrelated, it's been like that for a while.

None of the usb ports on the motherboard work (are powered), and the hard drive activity light doesn't blink, plus the hard drive is not clicking. This leads me to believe there is no communication with the cpu, aka the cpu is dead.

Hypothetically lets say my cpu and mobo are both toast. If I purchase new gear and put it in, will I be able to start up without reformatting my HD? Should I be prepared to lose that data...? Assume that I purchase nearly identical cpu and mobo.

I had backed up the hard drive about a week ago but did a considerable amount of work that week that I really do not want to lose.
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a b B Homebuilt system
November 8, 2010 9:45:36 PM

If you buy the same motherboard, or RMA it and get another, you will usually be OK without changing anything. Even if it's a totally different one, you can often boot in safe mode and back up anything before reformatting. Your CPU won't matter at all, the same or different doesn't matter at all.

I wouldn't purchase new gear though, you should be covered under warranty...
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November 9, 2010 3:48:42 AM

Im Betting Its The Board
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