Laptop undervolting experience?

[NewHopeTech]

I've heard good experience online of people undervolting the same laptop I have (Spectre X360 with i7 8550U) and having great results, so I'm going to try and see how I faired in the silicon lottery soon. I might repaste (not liquid metal) but I've heard that will only decrease temps by 3-4 degrees, but with undervolting that could be a significant delta from what I get now. For those of you with undervolting experience, how much did your temperatures drop and was there a noticeable effect in performance? Would undervolting the CPU at all benefit the iGPU performance? Maybe let it boost for longer because of lower temps?

 

Thanks for any advice or experiences you can share!

[Jurrunio]

28 minutes ago, NewHopeTech said:

I might repaste (not liquid metal) but I've heard that will only decrease temps by 3-4 degrees

HP Omen 17 with 8750H, before repaste it cannot complete Cinebench R15 with undervolt and disabling PL2 (so it's limited by 45w PL1) without thermal throttling.

 

Maybe HP did a crap paste job on my unit specifically, and the much bigger and heavier heatsink makes a bigger difference on my laptop to yours. Still worth repasting imo. (I'm using Cooler Master Mastergel Maker)

 

30 minutes ago, NewHopeTech said:

how much did your temperatures drop and was there a noticeable effect in performance?

8750H with 0.125V undervolt after repaste, runs Cinebench R15 at 3.5GHz at 45w instead of 3GHz. It only reaches 75C with the same settings, and can complete R15 with undervolt and 65w PL2 all the way while maxing out at 83C.

 

31 minutes ago, NewHopeTech said:

Would undervolting the CPU at all benefit the iGPU performance?

Yes, it will power throttle when the sum of power draw from the CPU and iGPU (socket power) reaches the PLs. Less CPU power draw = more room for the iGPU. You can also undervolt the iGPU btw.

[NewHopeTech]

15 minutes ago, Jurrunio said:

HP Omen 17 with 8750H, before repaste it cannot complete Cinebench R15 with undervolt and disabling PL2 (so it's limited by 45w PL1) without thermal throttling.

 

Maybe HP did a crap paste job on my unit specifically, and the much bigger and heavier heatsink makes a bigger difference on my laptop to yours. Still worth repasting imo. (I'm using Cooler Master Mastergel Maker)

 

8750H with 0.125V undervolt after repaste, runs Cinebench R15 at 3.5GHz at 45w instead of 3GHz. It only reaches 75C with the same settings, and can complete R15 with undervolt and 65w PL2 all the way while maxing out at 83C.

 

Yes, it will power throttle when the sum of power draw from the CPU and iGPU (socket power) reaches the PLs. Less CPU power draw = more room for the iGPU. You can also undervolt the iGPU btw.

Do you recommend using XTU?

[Jurrunio]

4 minutes ago, NewHopeTech said:

Do you recommend using XTU?

I use throttlestop because I know how to automatically start it up with Scheduler during boot but not XTU.

[NewHopeTech]

On 3/7/2019 at 12:21 PM, Jurrunio said:

I use throttlestop because I know how to automatically start it up with Scheduler during boot but not XTU.

Thanks! I ended up improving my cinebench R20 score by 20% and my unigine superposition score by 14%.

[genexis_x]

On 3/8/2019 at 12:27 AM, NewHopeTech said:

For those of you with undervolting experience, how much did your temperatures drop and was there a noticeable effect in performance? Would undervolting the CPU at all benefit the iGPU performance? Maybe let it boost for longer because of lower temps?

1. 2 scenarios: temp remains, clock speed increased or temp decreased, clock speed increased

2. No idea on iGPU performance

3. Yes it can boost longer, but this depends on other factors like firmware, PL setting etc

 

Use Throttlestop, XTU is a mess to me