Solved: i7 4765T Turbo Boost/Speed Step Weirdness

Toggle sidebar Toggle sidebar
B

brownatron

Jul 5, 2018
7
0
20
Hi all,
Hoping someone can help me with this weird issue.

I have an i7 4765T which doesn't seem to be Turbo Boosting correctly.
If I leave everything at default settings the CPU will speed-step down to around 0.8ghz at idle, as soon as I fire up Prime95 the CPU reaches it's base clock of 2Ghz but then does not seem to initiate turbo boost. *sadpanda*

Now interestingly if I switch the windows power plan to "high performance" and re-run Prime95 I get a Turbo Boost of up to around 3.7Ghz!
However it seems to run the CPU at this speed all the time and speed-step never kicks in to drop the performance back down...

I tried changing the power plan so that the minimum CPU speed was 5% but that didn't seem to make any difference :(

I've tried the CPU with a new install of Window$ and in 2 different motherboards (w/BIOS updates) and it all seems to be the same - which makes me think it's operator error :p

I'd ideally like to keep Speed-step enabled as this machine runs 24/7 and usually it doesn't have much work to do.

Anyone got any ideas?
 
Solution
B
Scratch that - better update for you:
Did some playing around in the registry and there are some hidden power settings within Windows 10 (and I assume 8/8.1 too) that you can enable to get finer control over the CPU.

What you want to do is go to:
HKLM\System\CurrentControlSet\Control\Power\PowerSettings

Here you will see a bunch of GUIDS for various power settings - each one of these corresponds to an option on the "advanced power settings" menu.
Here's the thing - not all of these are visible by default - they are just working away silently in the background.
Now each of the GUIDs listed under the "PowerSettings" reg key corresponds to a subsection on the power settings (see here for an example).
And then each GUID under that...
Sort by date Sort by votes
7

7664stefan

Honorable
Jul 18, 2013
355
0
10,960
Hey, have seen a similar behavior with my 2600k in the past. On which motherboard is the CPU running and what is the Bios version? I guess the issue is about a bad combination of bios and windows power management settings.
What makes me think is the 3,7Ghz you are mentioning. This CPU has a base clock of 2Ghz and boost of 3Ghz according to Intel.

Quote: The Core i7-4765T is the lowest TDP Haswell based quad core. It works at 2GHz, has four cores and eight threads and 8MB of cache memory. It supports DDR3 1600, at least officially, but turbo boost can get it all the way up to 3GHz.


https://ark.intel.com/products/75121/Intel-Core-i7-4765T-Processor-8M-Cache-up-to-3_00-GHz
 
Upvote 0 Downvote
7

7664stefan

Honorable
Jul 18, 2013
355
0
10,960
2,7Ghz...aha.
Are all the motherboard drivers, especially chipset, up to date? Can you enter the OC section of the mainboard and possible take a screenshot? Should check especially if EIST is enabled or any other setting might be limiting.
 
Upvote 0 Downvote
B

brownatron

Jul 5, 2018
7
0
20
Drivers seem to have made no difference.
I have read elsewhere that changing between "balanced" and "high performance" is utilizing C-States in the UEFI.
It seems like setting it to "high performance" pegs the state at C0 (off)
So I'll do some testing around this and see what I can find.
 
Upvote 0 Downvote
7

7664stefan

Honorable
Jul 18, 2013
355
0
10,960
Windows CPU power management should not allow more than 100% where then the details of the full performance are provided by the Bios settings. Where do you see "balanced" or "high performance" please? Right now have only access to a Win10 rig.
 
Upvote 0 Downvote
B

brownatron

Jul 5, 2018
7
0
20
Balanced and high performance are both options in the Windows power management options. (Just type edit power plan into the Start menu)
From the white papers I've read it seems that EIST gives the OS control over power and it's up to the OS to choose the correct C-state, so my theory is that by turning off EIST and manually configuring C-states I'll be able to get the CPU to turbo boost and down clock on idle.
I will test this on Sunday and hook up a power meter to do some readings.
 
Upvote 0 Downvote
B

brownatron

Jul 5, 2018
7
0
20
Solved!

After much experimentation I had to do the following:
Disable Intel C-states in the BIOS but leave EIST enabled.
Change the power plan in Windows to "High Performance" (so Turbo Boost works)
Modify the advanced settings on the "High Performance" power plan and set "minimum CPU state" to 0% and here's the crucial part:
Set "maximum CPU state" to 99% - hit apply then change it back to 100%.

Now the CPU has both EIST and Turbo Boost working.
I also hooked up a power meter to the server to see the difference - with ESIT not working the machine would draw around 85w at idle, with EIST on it draws around 63w so it's a fair difference for a machine that is running 24/7!

The only slight disappointment is that TB seems to be stuck at 2.6GHZ now as opposed to the 2.7/8Ghz I was seeing before...tbh this isn't a deal breaker for me and perhaps a more aggressive fan curve would resolve this.

All in all - one very happy camper :)
 
Upvote 0 Downvote
B

brownatron

Jul 5, 2018
7
0
20
Scratch that - better update for you:
Did some playing around in the registry and there are some hidden power settings within Windows 10 (and I assume 8/8.1 too) that you can enable to get finer control over the CPU.

What you want to do is go to:
HKLM\System\CurrentControlSet\Control\Power\PowerSettings

Here you will see a bunch of GUIDS for various power settings - each one of these corresponds to an option on the "advanced power settings" menu.
Here's the thing - not all of these are visible by default - they are just working away silently in the background.
Now each of the GUIDs listed under the "PowerSettings" reg key corresponds to a subsection on the power settings (see here for an example).
And then each GUID under that subsection corresponds to an option in that subsection.
Handily each of these keys has an "EXPAND" filed that gives you the mouse over comments :D

I went through each GUID enabling any I thought were relevant, but in the end only 1 was needed.
GUID be337238-0d82-4146-a960-4f3749d470c7 "Specify how processors select a target frequency when allowed to select above maximum frequency by current operating conditions."
Essentially Turbo Boost.

All you have to do is change the "Attribute" DWORD to "0" and now this option will show up in the power settings menu:
https://imgur.com/a/4mfMgcX

Then I simply switched the plan back to balanced saw that this option was set to disabled - changed it to "Enabled".
Ran prime95 and now I'm boosting to 2.9Ghz! :D :D
Wattage sitting comfortable at 68/70. :)

I am as happy as a pig in mud now and I hope that other people in the future can find this useful too :)

Have a wonderful day everyone!
 
Upvote 0 Downvote
Solution
You must log in or register to reply here.

TRENDING THREADS

Latest posts

Moderators online

Share this page

COMPANY
RESOURCES
FOLLOW
Top Bottom