25% performance difference on AI 9 HX 370 on battery vs AC adapter

Framework Laptop 13 Linux
1

I recently upgraded my Framework 13 mainboard from a 7640U to an AI 9 HX 370. As I’ve been running benchmarks on it, I’ve noticed that I get a fairly significant performance increase on AC adapter vs battery. For example, on Geekbench 6 single-core I get ~2,400 on battery and ~3,000 when plugged in, and for Speedometer 3.1 in Chrome, I get ~25 on battery and ~32 when plugged in. (From what I can remember, I don’t believe I saw this same level of performance difference on battery vs plugged in with the 7640U.)

I’m running Arch Linux and the latest 03.04 BIOS, and I’m running in the same “Performance” power profile on both battery and AC adapter. I also tried checking values for the CPU governor, scaling driver, and min/max frequency from /sys, and the values are all the same on both battery and AC adapter, so I’m not sure what else could be causing this.

Open to hearing any theories you may have to explain this!

Update: not sure if it’s relevant, but I am using the 55Wh battery, not the 61Wh battery (since it seems like it’s always out of stock!)

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7840U user here. I found when using battery, single core boost is 4.4GHz instead of 5.1GHz on AC. The difference might be slightly higher in AI 9 HX 370

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7840U user here. I found when using battery, single core boost is 4.4GHz instead of 5.1GHz on AC. The difference might be slightly higher in AI 9 HX 370

This seems like the most likely explanation. Although there doesn’t seem to be a way to configure this behavior/limit in the BIOS.