Pushing the Performance Limit of AM08 Pro

[djs93]

The AM08 Pro packs a top-of-the-line APU chip from the last generation – Ryzen 9 6900HX – into a mini PC footprint. This chip is usually used in thick gaming laptops, so it is interesting to see how it performs in a small desktop box. Average users can benefit from the easy mode selection knob on top of this machine. According to the manufacturer, the Silent, Auto, and Performance modes correspond to power consumptions of 20-30, 30-40, and 40-55 W. The performance mode should work for most casual gamers without worrying about breaking the system. For advanced users, some simple tuning can reveal the full potential of this power box.

To unlock BIOS-coded variables such as the boost duration and power limit, we first need to enter the BIOS and go to Advanced  AMD CBS  SMU Common Options. Here you will find a lot of things set to Auto by the manufacturer, which means that a default limit value has been set and cannot be changed in the OS by the software. To play it safe, we can change the System Configuration to 54 W, change PPT Control and STAPM Control to Manual, and enable STAPM Boost options. You will see that all the manual values are hardcoded to zero, which means that they are currently unlocked and has no limit. There isn’t much need to touch the voltage controls unless you want to spend hours fine-tuning the system to gain maybe a tiny little more juice out of the computer.

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The 6900HX chip has a Tjmax (max junction temperature limit) of 95 °C, according to AMD. This is what you will get by leaving it to Auto. If you change the TjMax option to Manual, you will find that it is hardcoded to 87 °C, and the system will be slightly more throttled to keep the chip below this temperature.

In Windows, we then use UXTU (https://github.com/JamesCJ60/Universal- ... ng-Utility) to control the performance tuning. By setting an Extreme preset, we essentially push to the very end of what the thermal and electric systems can do in this computer.

First, we test the CPU performance using CineBench R20. Auto mode gives 4564 (multi-core) and 601 (single-core), which is already impressive. The older AM06Pro carrying a 4800U has about 80% computing power of this 6900HX, and the graphics capability is less than 60% of the RDNA2-powered GPU in the current system. Setting the knob to Performance mode gives a slight performance bonus but much heavier noises. What really changes the game is the fully unlocked state. The multi-core performance increases by 20% to 5489 compared to Auto. This score has exceeded many beefy gaming laptops carrying the same chip.

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The GPU performance is on par with a discrete GeForce GTX 1050 3GB. However, it is still far away from the Radeon RX 6400 card despite the same core configuration. This is likely due to the power/electrical limitations and a lack of dedicated GDDR6 VRAM, which bottlenecks data exchange.

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Next, we test the power draw of the system with the unlocked UXTU Extreme profile.

When the computer is idle, the system power draw from the outlet is 10-12 W. When stressed by FurMark (768p 2X MSAA), the APU package draws 60-62 W with the GPU overclocked to 2.6 GHz. In this state, the outlet reads 100-108 W of power draw. The chip temperature stays around 88 °C.
Using FurMark CPU Burner, the APU package stabilizes at 50 W, with all cores reaching 3.9-4.0 GHz and temperature at 95 °C. Due to the high CPU workload, the chip is thermally throttled. If the CPU and the GPU are burned at the same time, the GPU clock can stabilize around 2.4-2.5 GHz. The CPU clock is reduced to about 1.3-1.4 GHz to make room for the GPU. The APU package draw is at about 74 W, and the CPU temperature stays between 95 and 95.5 °C. The system power draw at the outlet reaches a whopping 119 W, which exceeds the full capacity of the power brick written on the label! It is worth noting that the system is unstable under such an extreme load, and there is a good chance that the power will be dropped after a few minutes.

Conclusions: While the system design can be improved, the AM08 Pro is a competitive performance mini PC that is more than capable of handling everyday tasks and casual-to-mid scale gaming.
Pros:
• High CPU and GPU computing power packed in a small compartment
• Good connectivity with 2.5 GbE
• Easily serviceable and upgradable
• Advanced users can play with the BIOS settings and gain a significant performance increase
Cons:
• The fans are too loud under load and can be optimized with better thermal solutions
• Thermal dissipation in the storage chamber should be improved as there is no airflow to cool the RAM, M.2 drive, and 2.5” SATA drive (which directly stacks on top of the M.2).
• It would be great if the power button won’t rotate with the performance selection knob

Update 7/22/2023
I finally had time to take the machine apart completely and repaste the thermal grise with MX4. The peak theoretical performance further increased due to less thermal throttling, particularly the GPU (+3% due to repasting). CineBench R20 Multi-Core is now 121% of the auto mode, and Basemark GPU is 112% of the auto mode.

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[dd_milkshake]

I am curious how you get the GPU to run at 2600 MHz. Mine with 7735HS only goes up to 2200 MHz and stays there.

I do find repasting with a better thermal compound helped tremendously. Dropped the temp by 6-8C and the frequency curve is a lot smoother.

[djs93]

I am curious how you get the GPU to run at 2600 MHz. Mine with 7735HS only goes up to 2200 MHz and stays there.

I do find repasting with a better thermal compound helped tremendously. Dropped the temp by 6-8C and the frequency curve is a lot smoother.

I believe the GPU in 7735HS is default clocked at 2200 MHz, while 6900HX is at 2400 MHz. After I unlocked the BIOS restrictions as described in my post, I found that the GPU could reach 2600 MHz. It could be either due to GPU boosting settings or the fact that 6900HX is an unlocked processor. I'm not particularly sure of the exact reason, though.

[djs93]

I am curious how you get the GPU to run at 2600 MHz. Mine with 7735HS only goes up to 2200 MHz and stays there.

I do find repasting with a better thermal compound helped tremendously. Dropped the temp by 6-8C and the frequency curve is a lot smoother.

For another, mind to share how you disassembled the system for repasting? I was also stuck in the same place as the other folk who posted a review after I removed all screws but were unable to disassemble the system further.

[dd_milkshake]

I am curious how you get the GPU to run at 2600 MHz. Mine with 7735HS only goes up to 2200 MHz and stays there.

I do find repasting with a better thermal compound helped tremendously. Dropped the temp by 6-8C and the frequency curve is a lot smoother.

For another, mind to share how you disassembled the system for repasting? I was also stuck in the same place as the other folk who posted a review after I removed all screws but were unable to disassemble the system further.

I will come up with a service guide soon. But for the gist of it, remove the magnetic side panel, remove the SSD, loosen all the screws, then use something like a shim along the long edges to loosen the plastic clips, you should be able to pop the plastic cover out. Be on the lookout on the bottom though, there are two plastic clips that requires a little bit of finger finess to get it open.

[djs93]

I am curious how you get the GPU to run at 2600 MHz. Mine with 7735HS only goes up to 2200 MHz and stays there.

I do find repasting with a better thermal compound helped tremendously. Dropped the temp by 6-8C and the frequency curve is a lot smoother.

For another, mind to share how you disassembled the system for repasting? I was also stuck in the same place as the other folk who posted a review after I removed all screws but were unable to disassemble the system further.

I will come up with a service guide soon. But for the gist of it, remove the magnetic side panel, remove the SSD, loosen all the screws, then use something like a shim along the long edges to loosen the plastic clips, you should be able to pop the plastic cover out. Be on the lookout on the bottom though, there are two plastic clips that requires a little bit of finger finess to get it open.

Thank you, this is very helpful. I was afraid of prying the plastics after removing the screws that I could see, worrying that something else was still holding the case together.

[djs93]

I repasted the thermal grise and saw some moderate peak performance increase. Temperature is also much better. I highly recommend the manufacturer to use a better thermal compound and optimize how they are applied to the APU surface. I saw that the default grise was very thick, and the heatsink was not pushed against the chip surface with enough pressure, which created a thermal bottleneck. I also repasted my AM06Pro (4800U) and saw a huge improvement in temperature as well. The fan was pretty loud out of the box as it speeds up when the APU is > 60 degrees C. After repasting, the fan rarely speeds up under normal operation.