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LG Optimus 4X HD P880 Cooling Mod *Update*

OP KSH2014

14th May 2014, 07:05 PM   |  #1  
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As you already aware, there is a throttling problem with this phone. Really killing its potential.
I blame nvidia for making this chip 40nm and LG, not making a proper desing to dissipate the heat released by the SoC.

At default state, P880 behaves like a 100m sprinter. Fast at start, out of breath after the finish. That "finish" depends on the workload of the device and ambient temperature.
At very demanding games I can usually play about 10-15 minutes before serious lag.

This is not all off it.
Because of restrictive governor policies, some games that run smoothly on two core devices, runs like crap on this device. Default governor disables all but one core when there is load on graphics part. I assume this is also because of the attempt to prevent overheating.

So, the device is not running as advertised. This is my thought.
It seems, without serious underclocking and undervolting, one can not get a smooth experience from this device.

With the end of my warranty, I've started modifying the device. My aim is to keep the phone under heavy load with the highest speed as long as possible.

Before hardware level modification, I've rooted and BL unlocked the P880, thanks to great members of XDA.
I'm currently on stable version of CM 10.1.3. Stock kernel.

From what I've read and comfirm with my own experiments, there are two temp limits triggering the throttling. One is the battery, which is 43C. Other one is the core or the SoC which is 71C.
With these limiters, device is reaching its lowest speed of 475Mhz under 10 minutes @ 20-ish degrees celsius room temp. I use stability test v2.7 for achieving this. Under real life circumstances, e.g, games, this time differs between 10 to 20mins.

There is a warning on the battery. Says 40C max. Isn't that too low for this kind of device? With the help of this software I can increase "temp_throttle_skin" value easily to 50C. http://forum.xda-developers.com/show....php?t=2306980

With more headroom on the battery side, P880 drops no more to 475mhz up to 20 minutes of stress testing with Stability Test 2.7.
https://play.google.com/store/apps/d...into.stability

At 20th minute, battery was 45.5C. 4 cores running @ 1000Mhz. Core varies between 67-71C.

After a small mod of applying some Gelid GC-Extreme thermal compound over the metal piece installed on the SoC, I've got slightly better results.
At 20th minute with Stability test 2.7, classic mode, battery increased to 47.5C , 4 cores stayed at 1200Mhz and never dropped to 1000 but still hitting 70C. There is slightly better heat spread over the device.

SoC is not touching the main frame directly. Different from nexus 4, there is a small metal shield covering the Soc and memory. (Strange thing is, metal shielding has a hole over the memory part. There is a thermal sticker on that chip.) Only a small part of the metal shield is touching to the main frame. That is a weird material I've never seen before. Its surface looks like sponge but very hard to touch. Like sand paper. I applied the thermal paste on this material in hopes of filling the small gaps and achieving a better surface but it doesn't help so much. I think that rough surfaced material is not ideal to be there in the beginning.

I think, cutting some parts of that shield piece and placing thicker cu or alu sheet metal will be better approach.
I'm also planning to wait for some time for thermal paste to cure. From my experience with this same compound on the PC parts, it takes some time for best results.

All suggestions are welcome.
I also wonder what's your solutions for this throttling matter.

Here are the pics.



--UPDATE--

First, I want to say thanks to everyone who has send a reply to this post.

I'm back with more modifications and updates.

I wasn't satisfied with my previous modifications which was a simple thermal compound addition.
A proper test can not be done with lack of a custom kernel which has advanced software adjustment possibilities and of course a tool to make the adjustments.

Now I'm on CM 10.1.3 Stable with WerewolfJB kernel v009 [04-29-2014]. Making the speed adjustments with Trickster MOD app. https://play.google.com/store/apps/d...0.trickstermod

As for the modification, my first approach was replacing the thermal sticker with a copper plate.

Disassembling the P880 second time.


Notice the touch points of the mainframe.


The metal piece covering the SoC area and thermal sticker removed.


This metal piece between the main frame and SoC is an EMI shield and a heat medium which delays the heat transfer to the mainframe. If you attach the SoC directly to the mainframe, it makes better SoC cooling but battery gets very hot in return. This will eventually make the battery die quickly because heat is the number one enemy of the batteries.
If I could improve the heat transfer from SoC to both the mainframe and metal shielding piece, that might improve the cooling efficiency. That was what I wanted to find out before beginning to mod.

The thinnest copper piece I could find is 0.8mm thick.


0.8mm is too thick for a device which has 8.9mm overall thickness!


I was able to reassembly the device but that put a lot of stress both to the mainframe which has LCD on it and of course the fragile, over engineered, tightly packed PCB of the device. This was a bad idea.

I couldn't find thinner copper plates. At least this small amount.
Final solution came from an old slider style switch which has copper strips touching on each other. I 've found it laying around so destroyed it to get some copper strips, thin enough to use. After cutting to proper size, I've dealt with the corrosion first.

They are 0.35mm thick. I think this is the maximum that can be used without serious concerns.
I've applied thermal paste to both sides of the strips, cut the thermal sticker in half and put the thick part back on to the memory chip. This is the final design before reassembling the device.


I've prepared a test video. 20 minute stress run.

https://vimeo.com/97050916

My settings are stock. 1500mhz max speed with interactive governor.
This is the most torturing test. CPU+GPU test with gaming governor is nothing compared to 4 core stress test.
Last edited by KSH2014; 1st June 2014 at 08:45 PM. Reason: Update
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14th May 2014, 08:05 PM   |  #2  
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Quote:
Originally Posted by KSH2014

snip

you could disable the thermal throttling via an app (there is one in themes and apps section)

tegra overclock has the ability to disable (or change) temp throttling, and some of the kernels have removed throttling completely (atleast battery temp throttling, the one at 43 degrees)
14th May 2014, 10:14 PM   |  #3  
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Quote:
Originally Posted by Flying_Bear

you could disable the thermal throttling via an app (there is one in themes and apps section)

tegra overclock has the ability to disable (or change) temp throttling, and some of the kernels have removed throttling completely (atleast battery temp throttling, the one at 43 degrees)

Wouldn't that be dangerous? Removing the limiters completely?

Nvidia tegra 3 SoC limit is 85C. LG adjusted this to 71C. Maybe this is because of some other parts may be affected with such a high temp. All components are very tightly packed there you know.

Completely removing the limit not seems logical to me.
Operation within or close to the original limits should be achieved.

This could be done with undervolt/underclocking like many of the others did. But I want to get the most out of the available mass of the device as a heat sink.
14th May 2014, 10:26 PM   |  #4  
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Quote:
Originally Posted by KSH2014

Wouldn't that be dangerous? Removing the limiters completely?

Nvidia tegra 3 SoC limit is 85C. LG adjusted this to 71C. Maybe this is because of some other parts may be affected with such a high temp. All components are very tightly packed there you know.

Completely removing the limit not seems logical to me.
Operation within or close to the original limits should be achieved.

This could be done with undervolt/underclocking like many of the others did. But I want to get the most out of the available mass of the device as a heat sink.

you could leave temperature for shutdown. on 10a version of our software, LG had put 120c as temperature of shutdown (atleast that's what some people claimed, my device came with 10d), so having shutdown temp at 85 or 90 is safe (plus, i only hit this limit once, and that was with werewolf kernel which seems to have very high mpu voltage tables)

however i think throttling is useless - if you hit too high temperature, auto-shutdown will take care of any potential problem
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14th May 2014, 11:25 PM   |  #5  
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I'll try t buy a little fan and connect it to 2 1.5 V batteries and stick it with sth... or ill buy another back cover and make a hole and stick this fan to it
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15th May 2014, 12:20 AM   |  #6  
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Quote:
Originally Posted by gerciolisz

I'll try t buy a little fan and connect it to 2 1.5 V batteries and stick it with sth... or ill buy another back cover and make a hole and stick this fan to it

Why not?

If applied correctly, that may be the COOLEST solution.

Now imagine if someone takes this:
mugen-power-4400mah-extended-battery-for-lg-optimus-4x-hd-p880-with-battery-door (google it)

There is enough room between the camera and battery for this:
sunonusa.com/pdf/mm_fan_catalog.pdf(google it)

Take the blower one. Drill a hole and a side opening to the back cover. Add a thin micro switch. Something like you use with the tip of your nail.
So you only switch it on while you playing and not in your pocket.
Voltage is nearly perfect for direct feed with internal battery. A little resistance could be used. Power connection can be done with thin terminals placed between battery contacts.
No further heat sink modification may be needed. Because, simcard and sd card holders get really hot when CPU is hot. Cooling that part with such a method may be sufficient to drop the temps a little bit.

Feasible? Considering the price, effort and patience... Maybe not. But imagination is always good.

@Flying_Bear
I'll also look into that auto shut down idea. Thanks!
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16th May 2014, 09:58 PM   |  #7  
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All chips can take up to 250 C for short time. They are soldered on that temp. So don't worry.

Sent from my LG-P880 using Tapatalk
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17th May 2014, 10:33 AM   |  #8  
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Quote:
Originally Posted by KSH2014

Wouldn't that be dangerous? Removing the limiters completely?

Nvidia tegra 3 SoC limit is 85C. LG adjusted this to 71C. Maybe this is because of some other parts may be affected with such a high temp. All components are very tightly packed there you know.

Completely removing the limit not seems logical to me.
Operation within or close to the original limits should be achieved.

This could be done with undervolt/underclocking like many of the others did. But I want to get the most out of the available mass of the device as a heat sink.

I've reached like 95 C after changing throttle temps using tegra overclock app and overclocking (GPU 600@mhz, CPU 1700@mhz) with no undervolts.
It screwed my LCD up for about 30 minutes.Since then I'm using 85 C as CPU throttle temp and 50 C for battery and I faced no problems so far.So there is no point in keeping throttle temp at 71 C.I barely hit 80 C after undervolting anyway.
I'm pretty sure LG did this to keep the battery from runing out, not because it would actually damage any components.
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1st June 2014, 08:49 PM   |  #9  
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+ New updates and a test video added to the original post.

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