"Turbo boost" on old CPUs ?

[thekingofmonks]

I'm looking for a software that can, depending on loads, limit the power draw of old CPUs that normally run at a single clock speed, for the sake of power efficiency.

 

Specifically, one that sets a second, lower power limit and defines it as something equivalent to PL1, and the regular power limit as something like PL2.

 

Is there such a thing at all?

[Levent]

AFAIK that does not exist.

[jaslion]

What cpu you talking about?

 

Cpu's slow themselves down to a set min clock speed when higher performance is not needed. So it will already be as efficient as possible at stock.

 

If you wanna limit the max turbo in windows you can set max cpu performance by a percentage in power plans.

[Guest]

1 hour ago, jaslion said:

What cpu you talking about?

 

Cpu's slow themselves down to a set min clock speed when higher performance is not needed. So it will already be as efficient as possible at stock.

 

If you wanna limit the max turbo in windows you can set max cpu performance by a percentage in power plans.

Yes they can also set the minimum power to 0% for the CPU which is great for idling. 

[unclewebb]

@thekingofmonks

 

ThrottleStop can be used to manage the power limits of most Intel Core I CPUs as long as the BIOS has not locked this feature. Most 4th Gen and earlier CPUs are locked. What CPU do you have?

 

Intel CPUs enter the low power C states like C7 to save power. Slowing a CPU down makes efficiency worse, not better.

[thekingofmonks]

16 hours ago, jaslion said:

What cpu you talking about?

 

Cpu's slow themselves down to a set min clock speed when higher performance is not needed. So it will already be as efficient as possible at stock.

I'm talking about old CPUs from before speedstep was even a thing, like a Netburst or a Northwood

[thekingofmonks]

14 hours ago, unclewebb said:

Slowing a CPU down makes efficiency worse, not better

I'm not gonna argue and will instead ask you this: what do speedstep and long power do to the CPU?

[YoungBlade]

44 minutes ago, thekingofmonks said:

I'm talking about old CPUs from before speedstep was even a thing, like a Netburst or a Northwood

If it's CPUs from before SpeedStep existed, then as far as I know, software can't address the issue. That's a firmware limitation, below the OS.

 

Things like Intel XTU have the ability to slow down CPUs from within Windows, so with newer CPUs, it's obviously possible for root-level software to do that. However, if the CPU itself doesn't have a way to expose that functionality to the OS, then I don't see how anything other than underclocking in the motherboard BIOS could slow it down.

 

As far as I know, for CPUs that old, you need a system reboot after changing BIOS settings to change the clockspeed - up or down, doesn't matter.

[freeagent]

2 hours ago, thekingofmonks said:

I'm talking about old CPUs from before speedstep was even a thing, like a Netburst or a Northwood

No.

 

You would have to use a static clock and voltage.

[unclewebb]

6 hours ago, thekingofmonks said:

Northwood

I did not realize that you were interested in CPUs quite that old.

 

SpeedStep was designed to slow the CPU down when lightly loaded. Modern Core i CPUs use low power C states for most of their power savings. Slowing the CPU down with SpeedStep became a lot less important after the low power core C7 state became available in the 1st Gen Core i series.

 

Here is a comparison of the same CPU running at 5000 MHz vs 800 MHz.

The difference in power consumption when idle, fast or slow, is insignificant. 

 

https://imgur.com/IhCzWUp    

 

You are probably going to have a difficult time finding any software that supports the old CPUs you are interested in. Maybe you can use RW Everything and try to force different multiplier values into MSR 0x199. Not sure if that control register was used back then or not. 

 

Early Intel CPUs did not use power consumption data (PL1 and PL2). Power limit control started with 1st Gen Core i. The PL1 PL2 power limits started in 2nd Gen Core i. Intel continues to use this control method into the 14th Gen.  

 

22 hours ago, thekingofmonks said:

for the sake of power efficiency.

If power efficiency is important, grab any modern CPU. New stuff is way more efficient compared to any 20 year old CPU.