Undervolting mid 2015 15" MacBook Pro

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MacBook Pro 15" Retina Display metà 2015

Processore quad core Intel Core i7 da 2,2 GHz (3,4 GHz con Turbo boost), 2,5 GHz (fino a 3,7 GHz con Turbo boost) o 2,8 GHz (fino a 4,0 GHz con Turbo boost) con 6 MB di cache L3 condivisa.

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Hakan E @hknerdr

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Postato: 25 mag 2020

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Undervolting mid 2015 15" MacBook Pro

Hi,

I have mid 2015 15" Macbook Pro with i7 4870hq CPU.

I installed Volta app to undervolt and for measurement istats and intel power gadget.

With trial and error i found that i can go for up to -85mV. Can go for -95mV but it doesn't differ in terms of performance.

Tested the performance with cinebench r20, i get around %8-10 performance increase but i mostly get around 95-98 degrees temperature on CPU. It gets hot so quickly. I couldn't make it cooler much with undervolting. I think CPU idle degree is a little bit lower, like 55 to 47 degrees.

I installed mac fans control and increased the fans to their max rpms but didn't change anything.

Is there anything i can do more? What would be your recommendations?

I used cinebench as benchmark tool, what can i use in addition? I used geekbench but i get a little bit lower results like 5-20 points.

Thanks

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Whats the goal here? What is your use?

Are you into video or music production, a software developer, a gamer, or just someone who wants to push the system to the wall?

25 mag 2020 da Dan

@danj I want to push the system at its maximum and want it to produce less heat. But i work on complex excel sheets, so at that moments i need some more performance.

26 mag 2020 da Hakan E

IG Models - MacBookPro11,4

DG Models - MacBookPro11,5

26 mag 2020 da Dan

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Whats the goal here? What is your use?

Are you into video or music production, a software developer, a gamer, or just someone who wants to push the system to the wall? — Dan
@danj I want to push the system at its maximum and want it to produce less heat. But i work on complex excel sheets, so at that moments i need some more performance. — Hakan E

Dan @danj Rep: 473,4k Self employed contract worker 35 326 970 · Answer 1 · 2020-05-26T07:58:45-07:00

You are fighting two elements! Heat and performance! These often are polar opposites, as you get less heat with less performance or as you have discovered to gain performance you need to deal with the heat it creates.

Let’s start with RAM: There is a limit on what you can do here as this series has soldered RAM so you can’t get beyond what you currently have (hopefully 16 GB) so the OS uses virtual RAM which is leveraging the drive for what ever it needs to make up for the lack of physical RAM. That leads us to how big is the SSD drive and how empty it is. I strongly recommend having no less than 1/4 of the drive empty (500 GB and larger) and 1/3 for smaller drives. The less space the drive has the more it needs to engage wear leveling which pushes both the CPU and drive harder (heat).

I also recommend getting as large a drive you can get as the bigger drives are not only faster they also run cooler!

The next issue is the CPU and GPU’s: I would clean off the old thermal paste and apply a good nonconductive paste. I use either Arctic Silver 5 or Grizzly Kryonaut thermal paste. I also make sure the heatsink fins are clear of dust as well as the fan blades (the cleaner the system the better it can stay cool).

The next issue depends on which model you have: If you have the dedicated GPU model (DG) then I would install gfxCardStatus to disable the discreet GPU by using the integrated graphics engine only.

As far as altering the CPU’s voltage the app is not really able to do to much here as in this series the circuit is setup in a three phase design.

2015-15"-MacBook-Pro-CPU-power.pdf

Lowering the number of phases reduces the power to the CPU but at a cost! It is designed to lower the systems power draw in idle states (not while crunching any work loads). Basically, you are only reducing the phase from three to two and that’s as far as the firmware will let you in this series using the Volta app. Remember you also make the system less stable when you lower the power as well.

I think this is a waste of effort and the gains are so small its really not worth the data’s integrity.

Be cool man! A better approach is to improve the systems cooling. I use TG Pro as I find its the best tool allowing me see whats running hot and I can set a thermal point to pump up the fans (turbo).

As good as this system is (I have two!) It just can’t perform as well as a desktop which has better cooling.

I work on very large images which my MacBook Pro’s just can’t deal with when I stitch the discreet pictures together (30 to 90 images). I need the power of a Mac Pro to do it. I currently have a 6 core 2013 system and even it struggles with 64 GB of RAM and a 2TB blade SSD which is mostly empty at times.

Maybe you need to look at getting a newer system. the newest 2019 16” system is what I have my eye on for this fall. I tend to wait a good year before jumping to a new design. Even still I’m mostly buying it for its screen and keyboard, not as much for its CPU performance.

Thank you for your fast and detailed reply.

So in summary, you mean undervolting won't be beneficial? I see around %10 benchmark score increase in Cinebench r20, so does it make sense? In many articles, people get better performance with undervolting. So you don't agree?

I use istat menus instead TG Pro nearly same.

I thinking of clearing the fans and interior btw.

Why should i disable dediceted GPU?

Thanks — Hakan E
"Lowering the number of phases reduces the power to the CPU but at a cost! It is designed to lower the systems power draw in idle states (not while crunching any work loads). Basically, you are only reducing the phase from three to two and that’s as far as the firmware will let you in this series using the Volta app. Remember you also make the system less stable when you lower the power as well."

I didn't say that it wasn't beneficial but at what cost? Given you are trying to do spreadsheets are you willing to accept an error or corruption? If you are go for it! I personally wouldn't do it.

Apple has some very smart engineers. They do shave the corners just enough to get the best performance given the physical constraints of the system and with Steve's (now Tim's) directive to have as quiet a system as possible as well.

So the better direction (safer) is to focus on cooling, not lowering voltage if you want a stable system. This series already has power issues! Why is your Late 2013-2015 A1398 MacBook Pro randomly crashing? — Dan

Larry Lowe @cyberflyer Rep: 13 2 · Answer 2 · 2020-09-03T21:19:53-07:00

I have a mid-2015 15’ MBP with an i7-4980HQ 2.8 Ghz CPU, running Catalina 10.15.6.

Undervolting is valuable, but only when it is part of a complete effort, and calibrated properly.

My solution is:

1 Re-paste the heat sink using Thermalright CFIII paste, using the spread around the die method of application.

2 Thoroughly clean the fans, air ducts, inside of the system.

3 Find the Max Performance/Wattage Sweet spot for my system. In my case is Power Limit to 40 Watts.

4 Find the max performance undervolt setting. In my case, under volt by -75 mV.

5 Leave the Power Limit, Turbo Boost and Performance boxes checked in Volta.

6 Make sure that “csrutil enable —without kext” is run in terminal in recovery mode so the Volta KEXT will load.

7 Set the fans in iStat Menus to ramp up at 60C, 70C, 80C and 90C to 25%, 50%, 75% and Full Tilt Boogie.

8 If you are using an external monitor (Radeon R9 M370X driving it), make certain you have the MBP closed and the “Displays have separate Spaces” from System Preferences —-> Mission Control turned to OFF (unchecked) when running Cinebench r20.

The last has to do with funky temperature throttling the OS does when both the external and internal graphics are running at the same time. I think it is sort of a system bug. Simple answer is close the lid once you are fired up.

With all of this, I get an Idle set of temps around 50 C, moderate use like typing this in the browser of ~60C and in the high 70’s when running Cinebench.

And a long reliable cpu run at full utilization and 3.0 GHz without any temp or frequency throttling.

And an easily repeatable CB score of 1439.

The process to calibrate Volta is discussed at the Russian’s YouTube:

https://youtu.be/AW5BSW3PK7c

Renee Cousins @reneecousins Rep: 1 · Answer 3 · 2020-09-03T17:02:28-07:00

Renee Cousins @reneecousins

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Postato: 3 set 2020

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I have a 2014 MacBook Pro and while Volta helped, the next best solution was to replace the thermal compound — I used Thermal Grizzly Kryonaut, works awesome!

Additionally, you can use thermal PADs on the radiators to suck a tiny bit of heat out to the aluminum body. The MacBook case makes a great heatsink. It definitely spreads the heat out and the bottom can be a little warmer, but the system itself can run a lot stronger!

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