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Potentially fatal design flaw in the P370SM?


beezow

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I was originally going to put this one in my modding thread, but decided it might be better to have this in its own separate thread.

I present to you: the tale of a warped 780M.

This mod, while having a cooling aspect to it, goes far beyond that. I need to go into some detail on this one as this flaw can potentially cause the master GPU to die prematurely.

We all know the 780M has vRAM chips on the back, and having a heat spreader would be optimal for dissipating heat. Well this is what a Clevo 780M with a heat spreader looks like: (photo courtesy of Calibre41)

xXNYcxcl.jpg

And this is what the 780M in my P370SM looks like:

qXOHU68l.jpg

Alright then, so it seems I'm missing a heat spreader here. After some sleuthing, I was able to conclusively determine that all P1xxSM laptops have this heat spreader (part# 6-33-P15SL-101), the P570WM has the heat spreader built into the mobo, but for some reason the P370/375SM laptops got left out. Is this an engineering oversight, or did Clevo intentionally leave this out for some reason?

Well let's start by looking at the mobo after the master 780M has been removed:

PWoDVkrl.jpg

Keep this square outline in mind, I will come back to the significance of this later.

So as it turns out, the stock heat spreader from the P1xxSM machines can NOT simply be dropped in without some Dremel modding, have a look at these pictures:

uD3uABgl.jpg

A closer look at that protrusion:

dcG9ZQ6l.jpg

So it would appear that Clevo didn't include a heat spreader simply because they were too lazy to modify one to fit the P370SM. Which means they couldn't be bothered with less than 5 minutes of Dremel work to make the initial design. But is that really the case?

U4o6F7vl.jpg

There's just no way I could take a usable picture with the heat spreader resting on the mobo, but take my word for it that I've verified at least 5 times that the support foam on the heat spreader fits squarely (pun intended) into that square outline on the mobo.

At this point if I had to guess, Clevo perhaps in an earlier revision of the design had intended to include a heat spreader for the P370SM, but for whatever reason scraped this idea at some later stage, and the end result is what you see here. Now this wouldn't have been an issue if not for a much more serious problem that I discovered -- unbalanced mechanical load on the master 780M, causing the card to deform.

Seriously have a look at the pictures below:

There is a noticeable downward deformity on the top right corner of the 780M. (top right if you view the card top down with the pins facing downward)

uW8IbZml.jpg

Another view along the top edge of the card:

1qi4z4al.jpg

The top left is less affected, but a small gap still exists:

423nWcwl.jpg

This deformation is particularly nasty, as it widens the gap between the VRM chips and the thermal pads on the heatsink, to the point that the VRMs were barely contacting the thermal pad. (and I actually think the VRMs on the more deformed side weren't contacting the thermal pad at all) No wonder contact between the VRMs and the heatsink was poor. Doesn't help that the VRMs do the heavy lifting and run even hotter than the core.

You can probably appreciate how freaked out I was when I found out about this, but thankfully I was able to fix this with some 2.5mm pads.

If you need convincing that my master 780M warped due to an unbalanced load, have a look at this:

gK8Qzkjl.jpg

This truly a dangerous design flaw, and one that really pissed me off. All the other ones are just gripes that I can live with, but this one really had the potential to kill my card had I not caught it.

To Clevo's credit, the 880Ms in the P377SM-A (P375SM refresh) now do come with a heat spreader. So it seems that Clevo is aware of this issue and has taken steps to rectify it, so that's encouraging.

Btw, don't bother getting the heat spreader to fit the slave 780M in the P370SM, there's just not enough "depth" to accommodate the extra thickness of the heat spreader, yet this was no issue on the master 780M. So I think it's clear that Clevo did intend for at least the master 780M to have a heat spreader (if only just for load balancing purposes).

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  • 3 weeks later...

What I found is that the VR/memory heatsink is not flat for my P150EM. If the top is on flat then the lower part is lifted off, and if the lower part is flat then the top is lifted off. The SM series is likely the same since the aluminum base looks identical. Be careful trying to bend it straight because the aluminum is very brittle and will snap. I bent mine straight and snapped it, but the heatpipe was not broken so it was still usable. After bending it straight I then sanded the memory contact locations. The heatsink fits much better now despite being broken.

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The heatsink didn't look bent to me, at least not visibly so. In my case it really was because the 780M itself was bent rather than the heatsink.

The heatspreader doesn't do anything for thermals (well maybe it helps the vRAM on the underside to cool a bit), I use it mainly for structural support as I don't want my 780M to become increasingly bent over time and eventually snap.

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