Xiaomi MiPad 2 Tablet - Intel Atom x5-Z8500 SoC - Thermal Mod Using Thermal Pad 82°C -> 65°C

[RainfallWithin]

I noticed the Xiaomi MiPad 2 tablet I have was regularly reaching 82°C on it's highest core when multitasking. This tablet uses a Intel Atom x5-Z8500 SoC with 4 cores / 4 threads at a clock speed of 1,440 - 2,240 MHz. It's an interesting chip because it can run both Windows and Android natively without emulation. I'm running Windows 10 on it.

 

This system on a chip (SoC) has a TjMAX of 90°C, so whenever I multitasked it was only 8°C away from its maximum functioning temperature. This temperature was measured in Spring when the temperature is mild.

 

When I had previously disassembled the tablet to replace it's worn out battery with a new one from Nohon, I noticed that the SoC and its surrounding components were covered by a plastic shield, presumably to prevent them from touching the metal backplate.

 

I thought that I could remove the plastic cover and insert a thermal pad between the SoC and the metal backplate, in order to use the backplate as a heatsink. The idea was to reduce temperatures and possibly gain some performance too during periods where there would be a warm ambient temperature and I am multitasking.

 

 

 

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Control Test

 

 

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Thermal Pad Modification

 

I needed to determine which chip the SoC was, and also what the distance was between it and the metal backplate when the plastic cover was removed.

 

 

I determined which chip the SoC was by switching the tablet on and lightly placing my fingers against each of the components to see which generated the most heat. It was the largest of the metal plates that covered the SoC.

 

I needed to measure its dimensions to know the size of the thermal pad I'd need.

 

 

 

 

To calculate the distance between the SoC and the tablet's metal backplate, I placed a small ball of Blu Tack on the SoC, then put the backplate firmly back on the rear of the tablet.

 

 

 

The distance was 1.5mm between the SoC and the tablet's metal backplate. I decided to purchase a Thermal Grizzly Minus Pad 8 100x100mm at a thickness of 2mm. I chose the 2mm thick version to be sure that the thermal pad would properly contact the SoC and metal backplate in all areas.

 

I cut the thermal pad to the dimensions of the SoC's heat shield and placed it on.

 

 

 

 

 

 

The tablet's metal backplate still has the signs of milling from when it was machined; the circular pattern.

 

 

I put the tablet's metal backplate back on the tablet and screwed it in with the 2 screws on either side of the USB Type-C port.

 

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Thermal Mod Result

 

 

The result is that the SoC's maximum core temperature has been reduced from 82°C to 65°C; 17°C cooler!

 

The Cinebench R20 score after the thermal mod is 261, compared to a score of 258 before any modification. These results are within margin of error.

 

This shows that the maximum performance of the Xiaomi MiPad 2 tablet's Intel Atom x5-Z8500 SoC hasn't increased. However, the thermal mod will allow me to multitask on the tablet for long periods without the possibility of the SoC thermal throttling to a lower clock speed and losing performance, even on hot summer days where the ambient temperature can regularly reach 41°C outdoors.

 

It is nice to know that the temperatures are not close to TjMAX. When using the tablet, I can feel the metal backplate warm up, which confirms the thermal pad is transferring the heat from the SoC effectively.

 

The tablet's metal backplate bulges very slightly in the location of the thermal pad. I now know it would have been sufficient to purchase and use a Thermal Grizzly Minus Pad 8 100x100mm at a thickness of 1.5mm, instead of the 2mm one I bought. I went with 2mm to avoid the risk of insufficient contact and wasting money.

[DildorTheDecent]

17 minutes ago, RainfallWithin said:

The result is that the SoC's maximum core temperature has been reduced from 82°C to 65°C; 17°C cooler!

Have the average clocks increased at all? I'd imagine that they would have.

[RainfallWithin]

1 hour ago, DildorTheDecent said:

Have the average clocks increased at all? I'd imagine that they would have.

Thanks for your comment!

 

During the control Cinebench R20 test, the maximum clock speed reached on all 4 cores was 2,240MHz, and the 4 cores stayed at that frequency throughout. The reason the average is lower is because before and after the test the SoC's CPU cores were idling at 480MHz.

 

2,240MHz is the maximum clock speed achievable by the Intel Atom x5-Z8500 SoC. I was surprised that it wasn't throttling, even while being so close to TjMAX.

 

However, when I used the tablet to multitask for long periods, my impression was that the SoC was slowing down. This behaviour didn't show up in the control test, presumably because when I multitask, I am also loading the GPU as well as the CPU cores.

 

In the Cinebench R20 test after applying the modification, it also reached 2,240MHz and never dipped below that. The test takes about 20 minutes, which is more than enough time for the temperatures to equalise, so I felt confident the test results were accurate.

 

The fact that the CPU cores were at maximum frequency throughout both the control and modded tests makes sense because the results of each were within margin of error.

 

In the months since applying the thermal modification, I have seen the SoC is always reaching its maximum clock speed of 2,240MHz, and I haven't experienced the slow downs I used to while multitasking, i.e. watching a youtube video in picture-in-picture mode in one corner of the screen, editing pictures, drawing with my electronic pen, editing a spreadsheet in Google Drive, etc.

 

I have checked with the Intel Extreme Tuning Utility to see if there is any way to undervolt or overclock the SoC, but unfortunately those options aren't possible with this model.

[BARMAN]

I just did the exact same mod, after which i stumbled uppon your post :)

 

For me it wasen't so much the temperature, but more the thermal throttling when playing Youtube 1080p 60FPS. It would do it fine for a few minutes, but it would slowly clock the CPU down to about 0.7Ghz to a point where the video would be constantly loading. I have a few of these Atoms, and they all have their thermal issues, not so much when the CPU has high loads, more when the GPU is active (in my usecase videodecoding). That seems to generate a lot more heat, and most of the time the thermal solution is really poor. 

 

I also didn't even notice that much of a heat difference on the backplate. Sure it gets hotter on the spot where its touching the thermal pad, but it spreads out the heat pretty nicely. It makes the the whole thing more snappy (still pretty slow overal though, don't expect a miracle) when multitasking. At least it's somewhat useable now, too bad there's no real current Android development being done on this model... (not that i know of)

[RainfallWithin]

17 hours ago, BARMAN said:

I just did the exact same mod, after which i stumbled uppon your post

 

For me it wasen't so much the temperature, but more the thermal throttling when playing Youtube 1080p 60FPS. It would do it fine for a few minutes, but it would slowly clock the CPU down to about 0.7Ghz to a point where the video would be constantly loading. I have a few of these Atoms, and they all have their thermal issues, not so much when the CPU has high loads, more when the GPU is active (in my usecase videodecoding). That seems to generate a lot more heat, and most of the time the thermal solution is really poor. 

 

I also didn't even notice that much of a heat difference on the backplate. Sure it gets hotter on the spot where its touching the thermal pad, but it spreads out the heat pretty nicely. It makes the the whole thing more snappy (still pretty slow overal though, don't expect a miracle) when multitasking. At least it's somewhat useable now, too bad there's no real current Android development being done on this model... (not that i know of)

Thanks for your post. I found it interesting.

 

Yes, the thermal dissipation solution for these SoCs is almost nonexistent in many devices. My Xiaomi MiPad 2 tablet can now play 1080p 60fps YouTube videos smoothly since the modification, although with the occasional dropped frame if I look at the 'Stats for nerds' menu. The tablet couldn't handle this at all before, but 1080p 60fps videos played on local storage using PotPlayer have always been fine.

 

I sometimes use a Chrome extension called Turn Off The Lights, which allows me to block 60fps and play the videos at 1080p 30fps instead, which means I can have the video playing in picture-in-picture mode and do other things while the video is playing without the SoC struggling.

 

Is your tablet running Windows or Android, and is it the exact same model as mine, or a similar tablet with the same SoC?

 

Your comment about the little Android development for this tablet and devices with similar SoCs is precisely why I use Windows on mine. It's currently running Windows 10 Home version 2004. When there is a large 'feature' update, the update installs without errors, although they will always remove the Wi-Fi driver automatically for some reason, so I have to reinstall it after any feature update, which only takes 2 minutes. If anyone reading this ever needs a copy of the Xiaomi MiPad 2 Wi-Fi driver for Windows, just send me a message.

 

When I've been using my tablet for about 30 minutes, at least half of the metal backplate is warm.

[BARMAN]

On 9/29/2020 at 4:55 PM, RainfallWithin said:

Thanks for your post. I found it interesting.

 

Yes, the thermal dissipation solution for these SoCs is almost nonexistent in many devices. My Xiaomi MiPad 2 tablet can now play 1080p 60fps YouTube videos smoothly since the modification, although with the occasional dropped frame if I look at the 'Stats for nerds' menu. The tablet couldn't handle this at all before, but 1080p 60fps videos played on local storage using PotPlayer have always been fine.

 

I sometimes use a Chrome extension called Turn Off The Lights, which allows me to block 60fps and play the videos at 1080p 30fps instead, which means I can have the video playing in picture-in-picture mode and do other things while the video is playing without the SoC struggling.

 

Is your tablet running Windows or Android, and is it the exact same model as mine, or a similar tablet with the same SoC?

 

Your comment about the little Android development for this tablet and devices with similar SoCs is precisely why I use Windows on mine. It's currently running Windows 10 Home version 2004. When there is a large 'feature' update, the update installs without errors, although they will always remove the Wi-Fi driver automatically for some reason, so I have to reinstall it after any feature update, which only takes 2 minutes. If anyone reading this ever needs a copy of the Xiaomi MiPad 2 Wi-Fi driver for Windows, just send me a message.

 

When I've been using my tablet for about 30 minutes, at least half of the metal backplate is warm.

Yeah, i have the same MiPad2, and it's 64 GB. It's running Windows 10 Pro (20H2), and I did apply this debloat script. It gets rid of some unnecessary crap and frees up some memory, which definitely helps. Also came across this discussion on XDA which might be interesting to read.

 

I did my mod a little different though, and ended up cutting out a square from the shroud, so the thermal pad would make direct contact to the CPU and back housing. Seems to work just as well.

 

O and I had the exact same problem with the wifi driver not being properly installed after every major update. Not sure if this is still happening, and it's easy to resolve, but no idea why this happens...