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System doesn't POST after new heatsink installation

Last response: in CPUs
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March 27, 2012 9:21:31 AM

Okay, here's the rundown.

This morning, computer was running perfectly fine.

I got my new heatsink in the mail and started installing it. Installation seemed to go fine, no obvious problems or complications. I had to remove the Mobo from the case in order to install the backplate and I also removed the CPU from the socket in the installation process to better clean it.

I move everything back into the case and try to boot it up. Fans start and HDD starts spinning but there is no POST beep at all. Furthermore, the power button doesn't turn the computer off (even when held for 10+ seconds). In order to turn off the computer I have to physically hit the switch on the PSU. I wonder whether or not I knocked a cord loose so I take it out and completely reseat the CPU (recleaning and reapplying thermal paste as well, etc). This time, after getting the heatsink set up, I leave the mobo outside the case and only plug in the CPU and Mobo power plugs, along with the power switch front panel wire and the speaker. No ram, no GPU. Still no POST beep. I remove the new heatsink and put the old one back on and the problem sill occurs.

After messing around with various combinations of the above to make sure I didn't miss anything I tried troubleshooting the parts in my buddie's computer (he has the same series of CPU as I do and a similar motherboard). Normally, his setup posts perfectly fine. I try his CPU in my motherboard and my CPU in his motherboard and neither POST. As far as I can tell, both my CPU and motherboard are dead. I'm really at a loss here. Worse comes to worse I'll just buy a new cpu/mobo combo but I would hate to get it and then realize that my current stuff isn't actually broken.

Any help would be greatly appreciated.
a b à CPUs
March 27, 2012 9:43:58 AM

Could be a number of things. a static discharge may have damaged the motherboard, and over tightened backplate could have damaged the CPU.

given the situation you describe, im wondering if too much force has damaged BOTH the cpu AND the motherboard. Best idea would be to try to RMA both. if you can return them to the merchant, they will soon tell you if they are actually broken.
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March 27, 2012 9:51:15 AM

I've had both for over a year, I doubt they are still readily available to RMA.

I think at this point my best option will probably be just to get a new set of components. Even if the RMA is available, there's a good chance I would have to purchase both pieces again in addition to the shipping cost of the RMA.

One question though, I was throwing around the idea of the backplate causing a short on the Mobo. If that was the case, could the short permanently damage the board or would the problem go away when returning to the original heatsink?
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a b à CPUs
March 27, 2012 10:02:28 AM

Its very possible, but they generally would be designed not to do so. Besides, there's very little behind the CPU to actually short.

but if moving your CPU to another system also causes it not to boot, i would think its not so simple.

certainly worth a try though.

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March 27, 2012 10:13:03 AM

Yeah, I moved my CPU into a buddie's known working system and it was unable to POST. It just sat there with the fans spinning until I turned it off (though in this case I was able to hit the power button to turn it off, rather than having to hit the switch on the power supply).

During this time I also moved his working CPU into my motherboard to see if I could get a POST and it was unable to do so as well. So it seems that any system that I try using either my motherboard or my cpu is unable to post.

EDIT: Also, my question regarding the short needs clarification I think.

The question is this: If a short causes a system to not boot properly, would removing the object that is causing the short (in this case, the backplate of the new heatsink) allow the system to boot properly or would the initial short permanently damage the system?

I mainly ask for two reasons. If the system should be able to boot after removing the short, then by going back to my old heatsink, the system should of been able to boot. The second reason is that, if for some reason the new heatsink backplate is defective and causing a short, when I get my new components I don't want to install the new heatsink if causing the short will permanently damage the system.
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a b à CPUs
March 27, 2012 10:24:18 AM

A short would usually only prevent a system from booting, and not cause permanent damage. however it is possible that s short can do more serious damage if the power routed through as capacitor or other open line.

I have on more than one occasion shorted a motherboard with a standoff, stopping it from booting. but as yet haven't damaged one.

I would say it was very unlikely the back plate is causing a short though, but not impossible. it would be more likely to be a standoff or exposed cable.
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March 27, 2012 10:54:45 AM

I see. Though, in the case of a short, wouldn't moving the CPU into another working system result in a proper boot? I suppose it could be potentially possible that the my motherboard is actually working because the only test that I did to determine that was moving the CPU of my buddy into my system. If a short was present then it wouldn't of booted anyway.

That being said, I'm not really able to see a reason why suddenly a short is present when there wasn't one before
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a b à CPUs
March 27, 2012 10:58:40 AM

if it was the only problem then yes.

there are so many things that could be wrong here though that its very hard to know where to start, and the most basic ones might be too stupid to even bother with.

did you take your components to your friend or vice versa?

it could be the monitor, or video cable, causing the trouble. it could be a PSU, or any bad power cable.

Its time like this i wish i could just teleport round and have a look, but at the moment trial and error is about your only option. just systematically move through each possible cause and work to eliminate it.
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March 27, 2012 11:14:05 AM

Big Edit:

With my limited knowledge I would say that absolutely no post means a problem with one of the three following things:

CPU
PSU
Motherboard

I feel that the PSU was removed as an option because my CPU was unable to boot in his fully functioning system. If my PSU was the problem it would of worked fine in his computer.

For my attempt to remove the CPU and Motherboard as options I moved components around. I tried his CPU in my motherboard with only a PSU (with the CPU and the main Mobo power plugs only) and a speaker to check for POST. No ram or GPU or anything else. Nothing produced a POST. I tried my CPU in his fully functioning machine and there was no POST either. Right after trying my CPU I popped his back in and it booted completely normally.

So basically, there was no POST when either my CPU or my motherboard were present in any machine. It seems that because I'm fairly confident that my PSU works, the fact that there were no other elements present when I was testing his CPU in my Mobo shows that my Mobo is broken. At the same time, because the only element changed when testing my CPU in his system was the CPU, it seems that my CPU is also broken.
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