[MOD] A700 Heat & a Viable Solution!!!

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Beknatok

Senior Member
Dec 1, 2008
419
121
Chicagoland Burbs
UPDATE:

I wish I'd done some temperature benchmarking beforehand, but instead sourced the community to help out. Check out the various results on XDA... there are also results from two TF700 owners (in Europe) who were gracious enough to help me out.

http://xdaforums.com/showthread.php?p=28051518

First, it seems clear that my mod really didn't mitigate the heat issue enough... so don't bother.

Second, comparing the numbers between other A700's and the TF700... well, I'll let you draw your own conclusion on that one. :-(

---

Hi all,

As many of you have experienced, the A700 can get very hot under certain conditions. Mine got extremely hot to the touch after just an hour of gaming (Heavy Gunner, NFL Flick QB, and Cut the Rope), and crashed 2 or 3 times.

Well I decided to do something about it. Reading through the Service Guide (thank you paugustin!!!) & A700 teardown photos from another site, I came to some conclusions. First, from the looks of things, the back panel has some kind of metal plate lining, and 3 "pads" that closed the gap between the metal plate and several surfaces of the mainboard. My hope was that these pads were not simply foam pads but were actual thermal pads. I guessed that a bit of thermal paste might help the efficiency of those thermal pads... and if I got really ambitious, I could replace the thermal pads with larger ones (and paste those too).

Service Guide:
http://xdaforums.com/showthread.php?t=1716922

I followed the instructions in the Service Guide & opened up my A700 earlier tonight. I'm pleased to report that as long as you take your time, it's super easy to open up.

And lo and behold, my conclusions were accurate... the back plate is copper and the pads were thermal pads!

Back Plate:
https://www.dropbox.com/s/um556g6vtl7y99e/C360_2012-06-26-20-14-30.jpg

MainBoard:
https://www.dropbox.com/s/jka8gooiyqn9r2d/C360_2012-06-26-20-14-46.jpg

Closer Look @ the Thermal Pads:
https://www.dropbox.com/s/0j4e7wjfodwryk9/C360_2012-06-26-20-15-06.jpg


I took some CPU thermal paste I had lying around & dabbed some on:
https://www.dropbox.com/s/kvv99k3ghx73a00/C360_2012-06-26-20-17-24.jpg


Afterwards, I slapped everything back together, fired up NFL Flick QB and played for a half hour. I'm pleased to report that the A700 got warm but nowhere near as hot as it did in my prior gaming session. The "level of warmth" was what I'd consider mildly warm, comparable to my fiancee's iPad3, so definitely within reasonable tolerances.

I still intend to put the A700 through some more intense gaming tomorrow, but I wanted to write this post up and share it with everyone first. Hope folks find this useful and insightful!
 
Last edited:

FloatingFatMan

Senior Member
Apr 20, 2005
2,708
539
54
Nice discovery, but yikes! Thermal grease is meant to go on in a translucently thin layer or it ends up having the opposite effect! If you put that much between a CPU and it's cooler, you'd kill the CPU! :S
 

doanb555

Senior Member
Feb 24, 2012
64
6
Cologne
superawesome!

Yet still i'd like to wait for more people to evaluate the hardwaremodding before i go in there myself.

Still, kudos to you. :good:
 

Beknatok

Senior Member
Dec 1, 2008
419
121
Chicagoland Burbs
Nice discovery, but yikes! Thermal grease is meant to go on in a translucently thin layer or it ends up having the opposite effect! If you put that much between a CPU and it's cooler, you'd kill the CPU! :S

Except in this case, the thermal grease isn't going up directly against the CPU... it's going up against a thermal pad & large metal plate that is covering the entire mainboard.

Additionally, unlike a heatsink & CPU which are fitted together tightly, the back panel of the A700 & thermal pads do not contact anywhere near as tight to the mainboard plate. I fitted the two halves together, then pulled them apart again, to see how much the paste really spread out. This way I could better gauge how tight the contact was & remove any excess that got squished out. However, not much paste really did, telling me that the compression between the two isn't that great. That is why I'm toying with the idea of replacing the thermal pads entirely.
 

rushless

Senior Member
Jan 16, 2008
3,684
446
Hi all,

As many of you have experienced, the A700 can get very hot under certain conditions. Mine got extremely hot to the touch after just an hour of gaming (Heavy Gunner, NFL Flick QB, and Cut the Rope), and crashed 2 or 3 times.

Well I decided to do something about it. Reading through the Service Guide (thank you paugustin!!!) & A700 teardown photos from another site, I came to some conclusions. First, from the looks of things, the back panel has some kind of metal plate lining, and 3 "pads" that closed the gap between the metal plate and several surfaces of the mainboard. My hope was that these pads were not simply foam pads but were actual thermal pads. I guessed that a bit of thermal paste might help the efficiency of those thermal pads... and if I got really ambitious, I could replace the thermal pads with larger ones (and paste those too).

Service Guide:
http://xdaforums.com/showthread.php?t=1716922

I followed the instructions in the Service Guide & opened up my A700 earlier tonight. I'm pleased to report that as long as you take your time, it's super easy to open up.

And lo and behold, my conclusions were accurate... the back plate is copper and the pads were thermal pads!

Back Plate:
https://www.dropbox.com/s/um556g6vtl7y99e/C360_2012-06-26-20-14-30.jpg

MainBoard:
https://www.dropbox.com/s/jka8gooiyqn9r2d/C360_2012-06-26-20-14-46.jpg

Closer Look @ the Thermal Pads:
https://www.dropbox.com/s/0j4e7wjfodwryk9/C360_2012-06-26-20-15-06.jpg


I took some CPU thermal paste I had lying around & dabbed some on:
https://www.dropbox.com/s/kvv99k3ghx73a00/C360_2012-06-26-20-17-24.jpg


Afterwards, I slapped everything back together, fired up NFL Flick QB and played for a half hour. I'm pleased to report that the A700 got warm but nowhere near as hot as it did in my prior gaming session. The "level of warmth" was what I'd consider mildly warm, comparable to my fiancee's iPad3, so definitely within reasonable tolerances.

I still intend to put the A700 through some more intense gaming tomorrow, but I wanted to write this post up and share it with everyone first. Hope folks find this useful and insightful!

Fantastic for the XDA community, but the average buyer will be like the cheesey pop group Power Station and will "Feel the heat".
 

yeoldeusrename

Senior Member
Jun 30, 2011
132
83
Nexus 7
Sony Xperia XZ2 Compact
CAUTION!!!!!

OK maybe that's a bit strong, but as an engineer I have to question the logic employed.

First of all, the heat generated by the CPU, battery, etc. must exit the device. ALL OF IT!

Temperature of the back plate is determined by two factors alone: thermal resistance (e.g. insulation, heat pipes, air flow, fins, etc.) and the amount of heat transfer. I'm serious!

It appears that you have done nothing to affect the thermal resistance between the back plate and the air (e.g. adding cooling fins or increasing air flow). Therefore if your back plate temperature has decreased (and the air temp stayed the same), then we would conclude that heat transfer between the back plate and the air has DECREASED.

If hea
 
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yeoldeusrename

Senior Member
Jun 30, 2011
132
83
Nexus 7
Sony Xperia XZ2 Compact
If heat transfer from the plate to the air has decreased, then that means the heat transfer from the CPU etc. to the plate must have decreased as well!

My guess is that your thermal paste is producing a higher thermal resistance, as predicted by FFM! And it's deceptive because it's insulating the back plate from the CPU etc.

So where's the heat going? (I hear myself asking... myself.)

My guess is that it's dissipating through the tablet, getting distributed and absorbed and ultimately emitted more uniformly from the device. This would raise the internal temperature of the device, including the CPU! Hence the CAUTION!!!!!
 
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yeoldeusrename

Senior Member
Jun 30, 2011
132
83
Nexus 7
Sony Xperia XZ2 Compact
Your idea could have some benefit, though, and here's how i see it playing out:

If you decrease the thermal resistance between the CPU and the back plate, then the CPU would be closer to the temperature of the back plate (i.e. lower). But the back plate temperature won't really change because you still have the same total heat coming through and the same thermal resistance with the air.

As for spreading the temperature across the back plate more, I'm not sure you can do it more effectively than the copper plate that's already there. Not without insulating the most direct heat transfer path!
 

Beknatok

Senior Member
Dec 1, 2008
419
121
Chicagoland Burbs
CAUTION!!!!!

OK maybe that's a bit strong, but as an engineer I have to question the logic employed.

First of all, the heat generated by the CPU, battery, etc. must exit the device. ALL OF IT!

Temperature of the back plate is determined by two factors alone: thermal resistance (e.g. insulation, heat pipes, air flow, fins, etc.) and the amount of heat transfer. I'm serious!

It appears that you have done nothing to affect the thermal resistance between the back plate and the air (e.g. adding cooling fins or increasing air flow). Therefore if your back plate temperature has decreased (and the air temp stayed the same), then we would conclude that heat transfer between the back plate and the air has DECREASED.

Right, I'm aware of this.

The exact problem I was attempting to mitigate, is the transfer of heat between the mainboard cover plate and the back panel copper plate. I was theorizing that the thermal pads being used were not fitted well, thus not functioning optimally as designed to begin with. As a result, not enough heat was being transfered to the back panel copper plate for proper dissipation.

So either heat is being transferred to the back copper plate more efficiently now and dissipating more effectively... or the opposite as you proposed.

However, if heat transfer has decreased, wouldn't heat buildup would still occur within the small area between the back panel & mainboard? While it wouldn't be absorbing the same amount of heat directly from the thermal pad, heat would still build up over time and that should still be noticable no matter what, right?
 

Beknatok

Senior Member
Dec 1, 2008
419
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I'd also note that the BETTER solution would be to NOT combine thermal paste with the thermal pads, since as you point out, that can adversely affect thermal resistance.... but rather to replace the pads with better pads.

But I decided to be a guinea pig and try it out anyway.
 

yeoldeusrename

Senior Member
Jun 30, 2011
132
83
Nexus 7
Sony Xperia XZ2 Compact
Sorry I got distracted before posting my conclusion:

So my conclusion (prior to your latest comments) is that you can effectively lower the temperature of the CPU but not of the back plate. (unless you're insulating it from the CPU, which will spread the heat around and raise the temp of the internals!!!!).

I will consider your latest comments and repost!
 
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s300pmu1

Senior Member
Apr 15, 2011
443
174
The way I see it, the heat was not effectively transferred to the radiator. We have to remember that the case heat-up experienced by touch is not only the radiator, but the case itself heated by both the radiator and the air.

I'd assume that lack of crashes indicates smaller temperature of the CPU\GPU, as the heat is conducted more effectively by the paste to the radiator and dissipates evenly, instead of building up in one place and transferred to the case by air.
 

Beknatok

Senior Member
Dec 1, 2008
419
121
Chicagoland Burbs
It's times like this, that highlights the one minor missing flaw of the A700... there's no bloody temperature sensors that we can poll!!!

*bashes head against desk*

So unfortunately, all findings are really subjective unless yeoldeusrename's conclusions are correct and mine are totally incorrect, and my A700 decides to fry itself.
 

mearoth

Senior Member
Apr 28, 2011
53
23
It's times like this, that highlights the one minor missing flaw of the A700... there's no bloody temperature sensors that we can poll!!!
Well, i wouldn't be that sure. The A510 has them (at least separately for cpu and battery) and can be read by certain apps from the store. (E.g system tuner and battery monitor widget) so i would guess the A700 has them too.
Perhaps that helps


Sent from my A510 using xda app-developers app
 
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Beknatok

Senior Member
Dec 1, 2008
419
121
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Well, i wouldn't be that sure. The A510 has them (at least separately for cpu and battery) and can be read by certain apps from the store. (E.g system tuner and battery monitor widget) so i would guess the A700 has them too.
Perhaps that helps


Sent from my A510 using xda app-developers app

The two apps I tried, didn't show anything for temperature, but I just grabbed system tuner & it does register cpu temp! Yay! Will explore the app further to figure out how to record history for accurate metrics. Thanks for the hint.

Sent from my A700 using Tapatalk 2
 

rushless

Senior Member
Jan 16, 2008
3,684
446
Beginning to wonder if the heat and touch issues are why the 700 is priced the exact same as the 510. Nothing else apparently makes sense.
 

Itchiee

Senior Member
Sep 30, 2007
1,252
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Somewhere Else
I think I'm going to look into creating a heat shield to place against the rear cover.
2 to 3 inches across and 4 down on the right side should do it.

This is a great tablet otherwise and don't want to give up on it just yet.
Besides the Asus sound system is inferior.
 
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  • 8
    UPDATE:

    I wish I'd done some temperature benchmarking beforehand, but instead sourced the community to help out. Check out the various results on XDA... there are also results from two TF700 owners (in Europe) who were gracious enough to help me out.

    http://xdaforums.com/showthread.php?p=28051518

    First, it seems clear that my mod really didn't mitigate the heat issue enough... so don't bother.

    Second, comparing the numbers between other A700's and the TF700... well, I'll let you draw your own conclusion on that one. :-(

    ---

    Hi all,

    As many of you have experienced, the A700 can get very hot under certain conditions. Mine got extremely hot to the touch after just an hour of gaming (Heavy Gunner, NFL Flick QB, and Cut the Rope), and crashed 2 or 3 times.

    Well I decided to do something about it. Reading through the Service Guide (thank you paugustin!!!) & A700 teardown photos from another site, I came to some conclusions. First, from the looks of things, the back panel has some kind of metal plate lining, and 3 "pads" that closed the gap between the metal plate and several surfaces of the mainboard. My hope was that these pads were not simply foam pads but were actual thermal pads. I guessed that a bit of thermal paste might help the efficiency of those thermal pads... and if I got really ambitious, I could replace the thermal pads with larger ones (and paste those too).

    Service Guide:
    http://xdaforums.com/showthread.php?t=1716922

    I followed the instructions in the Service Guide & opened up my A700 earlier tonight. I'm pleased to report that as long as you take your time, it's super easy to open up.

    And lo and behold, my conclusions were accurate... the back plate is copper and the pads were thermal pads!

    Back Plate:
    https://www.dropbox.com/s/um556g6vtl7y99e/C360_2012-06-26-20-14-30.jpg

    MainBoard:
    https://www.dropbox.com/s/jka8gooiyqn9r2d/C360_2012-06-26-20-14-46.jpg

    Closer Look @ the Thermal Pads:
    https://www.dropbox.com/s/0j4e7wjfodwryk9/C360_2012-06-26-20-15-06.jpg


    I took some CPU thermal paste I had lying around & dabbed some on:
    https://www.dropbox.com/s/kvv99k3ghx73a00/C360_2012-06-26-20-17-24.jpg


    Afterwards, I slapped everything back together, fired up NFL Flick QB and played for a half hour. I'm pleased to report that the A700 got warm but nowhere near as hot as it did in my prior gaming session. The "level of warmth" was what I'd consider mildly warm, comparable to my fiancee's iPad3, so definitely within reasonable tolerances.

    I still intend to put the A700 through some more intense gaming tomorrow, but I wanted to write this post up and share it with everyone first. Hope folks find this useful and insightful!
    2
    Yes, I am aware but I'll see whats what if and when I take it apart.

    - Ordered 150 x 100 x 1.5mm - Thermal Pad to shape over the cpu/gpu area

    I'll let you know how it goes....
    1
    CAUTION!!!!!

    OK maybe that's a bit strong, but as an engineer I have to question the logic employed.

    First of all, the heat generated by the CPU, battery, etc. must exit the device. ALL OF IT!

    Temperature of the back plate is determined by two factors alone: thermal resistance (e.g. insulation, heat pipes, air flow, fins, etc.) and the amount of heat transfer. I'm serious!

    It appears that you have done nothing to affect the thermal resistance between the back plate and the air (e.g. adding cooling fins or increasing air flow). Therefore if your back plate temperature has decreased (and the air temp stayed the same), then we would conclude that heat transfer between the back plate and the air has DECREASED.

    If hea
    1
    It's times like this, that highlights the one minor missing flaw of the A700... there's no bloody temperature sensors that we can poll!!!
    Well, i wouldn't be that sure. The A510 has them (at least separately for cpu and battery) and can be read by certain apps from the store. (E.g system tuner and battery monitor widget) so i would guess the A700 has them too.
    Perhaps that helps


    Sent from my A510 using xda app-developers app
    1
    I've been unable to source a suitable, better-performing replacement thermal pad capable of bridging the (relatively) wide gap between SoC and heatsink. I'm thinking that a 'sandwich' solution, similar to what I've used on GPU VRMs before, may help.

    Basically you use a thermal adhesive such as Arctic Alumina to attach (permanently) a portion of metal such as Aluminium - or even better, Copper - to the SoC. You can then use your TIM of choice to bridge the air gap between the new 'heatspreader' and the heatsink inside the rear of the tablet. This eliminates the need for a 'liquid bridge' of TIM, which is largely ineffective.

    I've had success using this method on graphics card VRMs in the past, albeit they're always assisted by active cooling.

    I'm still looking at/working with replacement pads before I do anything too permanent. I'll report back in if I have any breakthroughs :good:

    EDIT: Fujipoly, more specifically their Sarcon range of products, looks like it may offer a viable solution, depending on the gap involved. Is anyone able to provide me with a hard measurement of the gap between SoC and copper heatspreader on the rear casing? Even just the thickness of the stock thermal pad would be a start.

    Sarcon SPG-30A looks particularly interesting. This is a 'high conductivity', form-fitting conductive foam/elastomer, which should scale to fit the die/gap reasonably well. Conductivity isn't as high as I'd like to aim for, but we're talking a low-voltage SoC so should be okay. There's a higher performing (6W/mK) putty which may also be viable (cost permitting).

    Now I just need to track some down :good: