Damaged CPU?

[lspa5657]

Hey everyone,

I just installed a new fan on my AMD Phenom II CPU, and after wiping off the old thermal paste, I noticed a small pit in the surface of the chip. I put the computer back together after fitting the new fan, and it seems to run fine. Now, do I need to think about getting a new CPU? Is this damage worth worrying about if the computer actually seems to run fine? Could this potentially result in further damage? What could have caused this? Overheating? Or am I concerned about nothing?

Thanks in advance.

 

[Vic Velcro]

Things you might consider:

Is the pit near the center of the CPU casing, or is it near an edge?
How large (diameter) and deep is the pit?
Can it be filled with thermal paste to avoid an air pocket?

Can you post a clear photo close-up? Did you take any pics while the heatsink and paste were removed?

It may have been caused by galvanic reaction (if paste coverage was not adequate and the metals making contact were dissimilar) or contamination (possibly salt from skin contact or solvent) before the heatsink was attached.

There are probably many possibilities for the cause of the pit.

 

[lspa5657]

Hey Vic,

Thanks for the response. Unfortunately, I didn't take any pictures before I reassembled the computer; I think maybe I should have. The pit was quite near the center, in the bottom left quarter of the chip's surface, was about a millimeter across and less than a millimeter deep. But it was obviously large enough to be noticeable. I wonder how thin the casing is on such a chip and whether it can withstand such damage without any kind of malfunctioning? Also, could it affect the functioning of the chip without completely conking out? Have you seen such damage before? Thanks!

 

[Vic Velcro]

I have seen a pitted chip casing, I have had more than one of mine get pitted over the past couple of decades. I've never had one penetrate the metal completely.

I don't know if I did the right thing or not, but I have always been able to massage some heat sink paste into the pit (like bondo on a car body), then apply paste the usual way before re-attaching the heatsink. This has never caused me any noticeable problem.

Since you've already put it all back together and it appears to be working, I'd watch it close for temps and glitches. If nothing manifests any time soon, I'd say your luck was good and leave it at that. If any problem does arise, you'll know that it turned out worse than you're hoping for.


In one instance (just once when I didn't think paste-filling would be adequate), I used a heat gun to warm up the CPU prior to filling a particularly bad pit with solder. After soldering, I put it in a cold oven and gradually brought the temp up until the solder reflowed a bit smoother. My next step was to lap the face of the casing with wet-dry sandpaper in stages from 400 to 2000 grit, then lap'd the heatsink too. After all of that, I pasted it, put the heatsink back on it, and used it for another year or so before upgrading.

 

[lspa5657]

I think your advice is sound. Just leave it as is and hope for the best. Worse comes to worse, I'll have to shell out for a new CPU, but I'll wait and see what happens. It sounds like it's not the most uncommon problem in the world since you've seen it happen a few times. What kind of glitches could possibly result? And by temps do you mean unusual temperatures?

 

[Vic Velcro]

Well, as far as glitches...

I've never had any from pitting, but I suppose if it went through the casing, the altered material could get into the core(s) and cause some signals to go the wrong way or maybe short some of the internal paths. I could only speculate.

If you notice significantly higher temps, pull the heatsink off, try to push some more paste into the pit, hit it with a heat gun or hair dryer to lower the viscosity of the paste so it flows better, warm up the heatsink, then re-attach it while both parts are still warm and gooey.

If, after that possible scenario, you still have glitches or temp problems, I'd pronounce the chip dead.

 

[lspa5657]

OK, thanks. I'll just hope for the best! When I first booted it up after changing the fan it was running at about 56 degrees celcius. It seems to have stabilized now though. Last I checked it was running at about 42 degrees. As far as I know that's fairly normal.

 

[Vic Velcro]

Indeed. It does take a bit for temps to stabilize when installing or reinstalling a heatsink. It takes time for the heat transfer paste to flow evenly within the gap between CPU and heatsink, as well as settle into the micro-voids.

 

[lspa5657]

Yep, I didn't know that but it sounds about right. Thanks again.

 

[madman7]

Did you do anything to damage it? Did you put the original HSF on it? If not, it could have been there all along. I say run it and see what happens.

 

[lspa5657]

Nope, the original CPU and HSF was installed by a computer shop guy. I only got to take a look at it for the first time recently because I installed one of those Arctic Breeze fans. It seems to run fine (and a lot quieter now BTW), so I'm just gonna run it for now. I'm just a bit concerned that any little glitches and lags are caused by the CPU, whereas they could just be due to hundreds of other reasons. I'm just not sure what sort of glitches could actually result from such a defect in the chip. Is it all or nothing? ie if the chip is damaged will it just fail to boot? Or is it more insidious than that?

 

[RGone]

I have seen some pretty good creases in the metal tops of cpus and in truth NEVER had an issue with them at all. Nada. Zip. This when I worked for a mobo company and some customers would send me their boards and cpus for testing. Of course when they received their parts back...they did not want problems and those with cpu dings and dents had no problems.

I would run prime 95 in blend mode for a couple of hours ensuring that cpu temps do not go over about 55C when fully loaded and then back to just using the thing before we all got fixated on the metal cover of the cpu. It is way more fun that way after passing a few hours of stable prime 95 blend testing and then back to computering and no more guessing at something that is no problem. Have fun.

 

[lspa5657]

Prime 95 in blend mode. I think that's the way to go.

Thanks for that.