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 Post subject: Overheating During Video after Reflowing Mobo
 Post Posted: Sat Jul 28, 2012 12:53 pm 
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Joined: Sun Feb 07, 2010 2:47 pm
Posts: 94
The following thread is for this system:

ThinkPad T40p (2373-G5U)
Operating System:Windows 7 32bit
P M 1.6GHz, 2GB RAM, 40GB 7200rpm HDD, 14.1 SXGA+(1400x1050) TFT LCD, 64MB ATI Fire GL 9000, SuperMulti Drive DVD(slim), Modem/Bluetooth, 1Gb Ether, 802.11a/b/g , Sec Chip, UltraNav, 9 cell Batt

For support from Lenovo on this particular system:

1. go to the Lenovo support page.
2. click the "Use Quick Path" link, and type in: "2373G5U".

When I type in "lspci" in a terminal in Ubuntu linux I get:

"VGA compatible controller: ATI Technologies Inc Radeon RV250 [Mobility FireGL 9000]"

I don't know if that helps, but I thought I would include it.

In December the system wasn't working after I dropped it. I successfully reflowed the motherboard by cooking it in a normal kitchen oven. The reflow was documented here.

Recently the system has been running hot, especially when viewing videos. If I try running a video for a long period of time, sometimes I get these little horizontal lines all over the display. The fan is almost always running. It didn't run so much before. If I stop playing a video, the system temperature comes down right away. It will get as high as 77 degrees Celsius and idling it runs around 38 degrees.

I'm thinking the only way to fix the system is probably to get a reconditioned motherboard. There are several models that will run in the T40p. Are there any you would recommend over the others?


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 Post subject: Re: Overheating During Video after Reflowing Mobo
 Post Posted: Sat Jul 28, 2012 2:50 pm 
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I don't see how a reconditioned motherboard would help, a chip doesn't generate more heat as it ages. However, a cooling system certainly can become less efficient over time due to fan wear, dust/dirt, and degradation of the thermal interface material. I would therefore recommend checking the fan to be sure it is clean and operating normally (at full speed), and if not I would clean and/or replace it. I would also renew the thermal interface material, especially that between the GPU and heatsink. Scott.


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 Post subject: Re: Overheating During Video after Reflowing Mobo
 Post Posted: Sat Jul 28, 2012 7:52 pm 
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Joined: Sun Feb 07, 2010 2:47 pm
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Thanks. I'm glad I didn't get the new motherboard.

I'm trying to do a good job on reseating the fan assembly. On page 105 of the "Hardware Maintenance Manual" a "Thermal Rubber" is mentioned. It attaches the fan heat sink to the GPU and cools it.

Image

The one that is on there now has a lot of dust on it. Maybe that is why it is not cooling the GPU.

I can't find an FRU for this thermal rubber. Do you know where I can get one?


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 Post subject: Re: Overheating During Video after Reflowing Mobo
 Post Posted: Sat Jul 28, 2012 8:42 pm 
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Joined: Thu Jan 15, 2009 1:27 pm
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Location: Stowmarket, Suffolk England
I think people use Copper shims to replace the rubber's as rubber is far less conductive than copper!


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 Post subject: Re: Overheating During Video after Reflowing Mobo
 Post Posted: Sun Jul 29, 2012 9:50 am 
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Thanks, I'll try that. As soon as I do it I'll post the results here.


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 Post subject: Re: Overheating During Video after Reflowing Mobo
 Post Posted: Sun Jul 29, 2012 10:56 am 
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unckybob wrote:
I can't find an FRU for this thermal rubber. Do you know where I can get one?

That "thermal rubber" is called a Thermal Conductive Pad (also known as a "Gap Pad") and is only sold pre-applied by Lenovo. Just like with grease there are a number of different types available but the type I linked above is close to what Lenovo uses, with a thermal conductivity rating of 4 W/mk (higher is better). For reference, air has a thermal conductivity of 0.024 W/mk. Here is an example of some of the best pad material, with a rating of 6 W/mk.

Note that gap pads have less thermal conductivity than good quality thermal grease, which has a rating of 8.5 W/mk. The problem is that grease isn't designed to fill gaps, and can only be used when the component and heatsink are in direct contact.

The easiest solution would be to replace the existing pad with one of higher thermal conductivity. You could also try to fill the gap with a shim of copper (385 W/mk) or aluminum (205 W/mk) as long as you can get good physical contact from the chip to the shim, and from the shim to the heatskink (I would use thermal grease on each side of the shim). If you use a metal shim then you must insure that no short circuits are created, and that the shim will stay in place. Scott.


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 Post subject: Re: Overheating During Video after Reflowing Mobo
 Post Posted: Wed Feb 13, 2013 12:20 am 
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Joined: Thu Jun 07, 2007 10:54 am
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Location: Minneapolis, MN
Implied by the Hardware Maintenance Manual for my T61 (it's unclear if it's speaking of installing a new Fan assembly, a used Fan assembly, or both), thermal grease should be re-applied to the rubber pads when re-installing the Fan assembly. I'm curious as to whether the pads assist in cushioning the CPU die from the weight of the Fan assembly and pressure from typing on the keyboard.


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