No, it isn't possible to exceed the 25W limit on the i5-8250u with a modified BIOS.
No, it isn't possible to exceed the 25W limit on the i5-8250u with a modified BIOS.
Hey there, I've looked up online but couldn't find a clear answer to your question. Could you check if it's possible to increase the i5-8250u's long-term power limit past Intel's default 25W "configurable TDP-up"? Your machine is an Acer Aspire A515-51G-55F1, and you're using a semi-custom cooling setup. Someone suggested that VRM parts should handle up to 45W with a fan aimed at them, and your setup includes an eGPU via ADT-LINK R43SG which won't draw more than 65W. Updated September 20, 2021 by Hentrox
You want to achieve this because it helps clarify your goals and ensures a better outcome.
It seems the configuration isn't clear. You probably need to verify if your laptop originally had a higher TDP CPU and whether its power delivery was restricted by the VRM.
I believe boosting the CPU voltage beyond normal isn't wise. It might lead to your motherboard failing, the VRM overheating, and then the power brick giving out—essentially ending everything in a flash. Heed someone who lost their laptop from an experiment: just avoid it.
The 8th Gen U CPUs offer a lot of adaptability and can operate efficiently even above their 15W TDP specification. Intel does not enforce strict power caps for these processors. Typically, Acer implements an embedded controller (EC) to maintain the 15W TDP limit. It’s unlikely your Acer laptop will allow sustained operation at the adjustable 25W level indefinitely. Acer generally keeps these CPUs within the 15W boundary. I’m not aware of anyone successfully bypassing this restriction. The Lenovo C930 shown in the image bypassed such constraints by not using an EC, making it straightforward to exceed 15W. Run ThrottleStop and share a screenshot of the TPL window. There are three distinct power restriction categories for Intel CPUs. ThrottleStop provides access to MSR and MMIO limits, yet EC power caps remain in effect for some manufacturers. If both MSR and MMIO limits are correctly configured and your system still throttles under load, it’s the EC limits that dictate performance. Changing these settings isn’t straightforward.
I've shared the screenshot. Previous tweaks with throttlestop and xtu didn't alter PL1. It seems unlocking engineering or advanced settings via a modded BIOS won't affect it, since a separate physical EC handles that lock.
Adjust the ThrottleStop TPL window to match the desired display. Setting PL1 and PL2 to 44W will handle MSR power restrictions. Reviewing the MMIO Lock option will manage MMIO power limits. Click OK and perform a benchmark such as Cinebench R20 while the Limit Reasons window remains active. https://www.techpowerup.com/download/maxon-cinebench/ Are you noticing any PL1 or PL2 power restrictions in the Limit Reasons section while the CPU is under full load during this test? Is throttling occurring at 15W or below? If power limits are being reduced significantly below the 44W setting, it’s likely the EC is restricting your CPU. You may attempt to flash a modified BIOS only if you’re confident it’s safe. There’s no benefit in damaging your laptop trying to overcome this restriction. I doubt a BIOS update will resolve this issue. With a modified BIOS, you might adjust MSR and MMIO limits, but the EC power cap should remain unchanged. If you install a modified BIOS, remove the ThrottleStop.INI file before running ThrottleStop to clear any previous power limit configurations.
I adjusted the settings from my screenshot, then executed cinebench. The CPU started at 30W and reduced to 15W after a few seconds, remaining stable. It’s fine if I damage the BIOS—I can reinstall the original or an unlocked one. I’ll use a SPI programmer that clips to the chip and force-flash it on another machine. If I risk permanent harm (though I’m careful), it’s acceptable since the cost was only $150 NZD. The SPI programmer should arrive next week, so I’ll update here after flashing an unlocked BIOS. Thanks for your feedback so far.
Side note: Someone in the comments claims there’s no 'embedded controller'—see this link: https://www.reddit.com/r/intel/comments/...be_raised/