Accidentally removed thermal pad for north bridge or southbridge on T400

I have another thread on here about a thermal paste application that I did tiday, but I'm just realizing that I might have made an important mistake so thought I should make a new thread in hopes of getting more responses.

Anyhow, on my heat sink, the CPU and GPU were covered with thermal paste, and the southbridge (?) had what I now assume was a thermal pad. I thought I had read to remove this, so I peeled the whole thing off. It was probably 0.76 mm thick or so. I then covered the southbridge (?) with thermal paste and reassembled the laptop. It's running OK, but I haven't done anything really demanding, and I'm afraid the heat exchanger isn't making contact with the southbridge.

Is anyone familiar with the inside of the T400? Can you tell me what this is, and if I'm ok with the thermal paste, or if I need to disassemble and put a pad back in there. And if so, can you recommend a pad? And would it be ok to use my laptop for office work until I fix that, or should I fix that immediately?

Thanks.

Oh and here is a possibly relevant thread that I found elsewhere forum.thinkpads.com • Where to buy thermal pad for T400 (2767-CP6) heat-sink?

 

I'm going to guess that it was actually covering the NorthBridge, since I don't have a T400 to crack it open.

Run a stress test like Prime 95 and see how the machine behaves. In the long run, the pad should be replaced, but there's a decent chance that you might not need to be extra expedient about it.

Good luck.

 

Do you know where I can get this pad? Is there any way to find out how thick it would be, or should I go digging through the trash to find and measure the old one haha

I can't beleive I peeled it off of there... Doh!

I was able to recover the old one from the trash. It's very thin (0.5 mm maybe), and you can see the impression the component made into the pad. So, if the north bridge isn't touching the heat exchanger, it's dang close. I suppose I will try Prime 95 and see what happens...

 

There are sellers on feebay who have all types of pads, but you'd need dimensions. Some digging might be required...

Don't stress yourself over it though. Stress the machine instead and find out where you really stand.

 

Thanks ajkula66! I downloaded Prime 95, but can you by any chance point me towards a resource or guide that outlines exactly what tests I should run with this?

 

Hardware - Stress Test With Prime95 - Windows 7 Help Forums

Run the prime95 thread tests and keep an eye on the temperatures... I believe 2-3 hours testing will be fine

 

I just started the default test and its got my temps up to 85 C!

 

That's fine. As long as the machine doesn't shut down within an hour, you're safe...

 

Ok, I'll let you know what happens. I'm nervous!

Soif the machine doesn't overheat and shut down, does that mean I'm ok without replacing the thermal pad on the northbridge?

And I'm sorry for all the stupid questions, I don't know what I'm doing obviously (haha).

 

I'd still replace the pad, but wouldn't pull my hair out if I didn't get it done tomorrow...

 

The "blend" Prime 95 stress test has been running for an hour now. Temp seem to max around 91 C, although I did see it get up to 93 C once. I was running CFD simulations last weekend that were overheating the machine within 20 minutes. I should run that again tomorrow to see how it compares with the Prime 95, but from what I can tell, reapplication if the thermal paste (and removal of the pad) is better than what was in there previously!

Ajkula66, do you still think I should open everything back up and put in a new thermal pad for the northbridge? I'd like to avoid that if at all possible. This is my work machine and I need to rely on it, and don't want to have to do that unless necessary. Is there any Prime 95 test that would tell me I don't have to do that? Should I run this overnight to see if it keeps going? Does this thing create a log, incas rthe machine shuts off!

 

As previously stated...

 

Thanks ajkula66. Would any go the generic pads from eBay work, as long as the dimensions fit? Also, I'm assuming I have to reclean and reapply the heat sink pastes, but can you let me know iii wing and can somehow reuse that?

On the upside, I'll get a chance to see the quality of my paste application from yesterday!

 

I'd clean and re-apply...and yes, as long as the dimensions match (mostly the thickness, really) you should be fine...

Good luck.

 

Thanks ajkula66, I really appreciate your help with this. I have no idea what the heck I'm doing, but I feel a lot more comfortable doing this a second time than I did doing it for the first time yesterday haha!

 

To tell you a little story OT, make you feel better and get a chuckle out of it...

So I've pulled apart a zillion laptops, right? I should be able to do most of the stuff blindfolded...anyways...

Working on a tiny (as in less-than-2lbs-10.4" XGA) Japanese-market-only Panasonic CF-R4 some years ago. All thrilled that I finally found one since it was a perfect travel machine.

Mind you, these babies don't have fans at all. Passive cooling only, and the heatsink is likely 1/5 of their total weight. However, the price to pay for their size/weight (amongst other things) is the fact that one has to rip apart the whole laptop in order to install a hard drive...talk about being spoiled by ThinkPads...

So I put the machine back together, boot it up, and am observing the temps...the poor thing gets *really* hot *really* fast, to the point of being uncomfortable to touch, and I'm like "WTH??????????" and then...

I noticed the heatsink sitting on the floor, right by the laptop's side. Never put the darn thing back in.

So yes, stuff happens...

 

So you do your work on the barn floor at the Farm? Hands and knees and belly on the floor? Please get a workbench.

 

Of course I do. I've trained my thoroughbred FlexView horses to bring me the tools as well...and they can tell a Philips screwdriver from a regular one as well...

All jokes aside, due to a nasty on-the-job accident a couple of years ago, I can't sit "normally" for an extended period of time. That's why many a times I work sitting on the floor with my legs crossed. I know it sounds beyond weird, but that's the only way for me to get comfortable...

 

The thermal pad Lenovo used was 30x30mm, but the chip is only 10x10mm, so there was a considerable area of the thermal pad that wasn't in contact with the chip. I'm assuming it's OK to cut my thermal pad to a smaller size (e.g. 15x15mm) - can anyone confirm that? I just wanted to check before doing it, and then realizing there was actually some reason the thermal pad was so much bigger than the chip.

Thansk!