How to edit TDP limit in BIOS ?

fejerm

Hey guys!
I own a Helios 500 with 8750H  cpu.
I have an unlocked BIOS so all settings all available. 
I want to rely on the Predator Sense as little as possible for 2 reasons:
1) when enabling CPU power Limit MAX in the software it changes PL1 45W / PL2 56.250W to PL1 56W / PL2 70W 
2) When enabling  MAX Pwr limit Predator Sense automatically applies -125mV undervolt

Now I want to add more undervolt and set PL1 70W / PL2 70W.

How can I do this? I am not really familiar with Insyde BIOS. Could someone help me out who knows this type of BIOS inside-out? What do I need to set?

The menu I think is responsible for this is under advanced -> Power & Performance



Inside this I need CPU Power Management Control



After this I went inside Config TDP Configuration



Inside here I have got this:


However here I am stuck. I have set Power Limit 1 and Power Limit 2 to 70W in the blue area (which can be edited) and then rebooted, however these settings did not get enabled because after reboot the factory TDP limits (45.0/56.250 in the black area) did not change to 70/70. What did I do wrong? What do I need to set?

Thank you for your help !

ps: A fair warning to anyone with unlocked BIOS. I have removed the factory installed cheap 2666 Mhz CL 19 RAM modules and installed better quality 2666 Mhz modules with cash latency 15.  I have set these modules in the BIOS to run at 2800 Mhz however I have tried to run them at 3000 Mhz (You know, for science ), but the laptop refused to boot. I have tried to sort the 2 pins responsible for CMOS reset, however the EC got so damaged from the above used RAM setting that even after CMOS reset the BIOS was not able to rewrite the default EC. Only solution was to reflash the entire BIOS with an SPI programmer. So be careful when you edit memory settings, it may brick your laptop which can only be fixed with an SPI programmer ! 

vanadium

Any wrong setting in unlocked bios on Helios 500 needs a reflash. Bios settings are "written" into the bios, that's why a reset CMOS isn't enough. Regarding the power limits, you are on the right screen. Simply set the values on Power Limit 1 and Power Limit 2, as desired (in milliwatts as stated by bios help). However, I achieved the best results by simply undervolting the CPU in overclocking section. Mine runs at -200mV rock stable.

I tried to up PL1 to 56250, but the fan was running much more often and performance wasn't really improved in my usage.

Regarding RAM, if you increase the RAM speed, make sure to increase timings like CAS latency as well. Mine runs at 17-17-17-39 @ 2400Mhz, but requires 21-21-21-43 to run at 2933Mhz (and that's the maximum speed I was able to reach). See my blog post:

https://octoperf.com/blog/2018/09/02/acer-predator-helios-500-mods/

vanadium

Any wrong setting in unlocked bios on Helios 500 needs a reflash. Bios settings are "written" into the bios, that's why a reset CMOS isn't enough. Regarding the power limits, you are on the right screen. Simply set the values on Power Limit 1 and Power Limit 2, as desired (in milliwatts as stated by bios help). However, I achieved the best results by simply undervolting the CPU in overclocking section. Mine runs at -200mV rock stable.

I tried to up PL1 to 56250, but the fan was running much more often and performance wasn't really improved in my usage.

Regarding RAM, if you increase the RAM speed, make sure to increase timings like CAS latency as well. Mine runs at 17-17-17-39 @ 2400Mhz, but requires 21-21-21-43 to run at 2933Mhz (and that's the maximum speed I was able to reach). See my blog post:

https://octoperf.com/blog/2018/09/02/acer-predator-helios-500-mods/

fejerm

"Any wrong setting in unlocked bios on Helios 500 needs a reflash"
That is not entirely true. Since then I have set incorrect cas latency (CL14 instead of CL15) and incorrect CPU values which caused the laptop to not boot, however I was able to reset the BIOS by sorting the pins responsible for CMOS reset + disconnecting the battery for 30 sec.

These 2 pins need to be sorted (+ battery disconnected):


Yes, I now have some extra PCH cooling+a bios reset button so when I need a CMOS clear I do not need to completely remove the entire back panel, only the RAM/SSD cover

But back on topic:
I feel so stupid...I was setting the right thing all along, however I "forgot" that those values are in milliwats so I need to set "70000" and not just "70"...thanks for the tip

vanadium

How is the PCH doing with the heatsink? I may put a heatsink there too. Which adhesive thermal compound did you use? Awesome finding for the bios reset cmos pins! I wouldn't solder anything on the motherboard myself, thought. Requires way too much precision and adequate tools for me!

fejerm

Luckely I know someone really skilled who did an excellent job

As for PCH temp...if I can trust HWinfo reading it actually did nothing. Before I was getting 62C max in aida64 stress, now I am getting the same.