Asrock z170m-itx/ac and 3200Mhz memory = no boost

Nobody?

bertybassett wrote: Asrock z170m-itx/ac updated bios to v2.60, reset bios to default. raijintek 0P105246 - Raijintek Aidos Direct Contact CPU Cooler (also tried a Corsair h45 AIO Rad cooler) G.SKILL TridentZ Series F4-3200C16D-16GTZB 16GB (8GBx2) DDR4 3200MHz C16 1.35V Memory Kit Corsair CP-9020096-UK VS Series VS450 ATX/EPS 80 PLUS 450 W i5-6600k At default bios settings with no XMP I can boot to windows and run prime95 v28.9 at 3900Mhz and it stays at 3900Mhz all day long thanks to Intel turbo boost. Now when I set XMP on and speed 3200Mhz I can boot to windows and run prime95 v28.9 and I get 3900mhz for only 20 seconds before it drops back to 3500Mhz and stays at this lower speed for 24 hours. Idle windows temp is about 28c, max temp recorded temp of any core is 75c and all the cores bounce around the 68c mark under load in prime. When I test with XMP turned on at any speed above 2133Mhz the same happens. Someone suggested I try increasing the memory of the RAM. Is this a good idea? Should XMP change the volts automatically? From the asrock web site I can see that this memory is compatible.

It stays at 3900MHz constantly (on all cores) thanks to Intel Turbo boost? Actually that is wrong.

Turbo Boost to 3900MHz is the Turbo speed when ONE core is heavily loaded, and the others aren't.

In the UEFI in OC Tweaker, CPU Configuration, if you set CPU Ratio to Per Core, you'll see the four core Turbo multipliers for the CPU being used, if it has Turbo boost. They are labeled One Core, Two Cores, Three Cores, and Four Cores. Note that the labels are not Core One, Core Two, etc.

For the i5-6600K, that is 39, 38, 37, and 36. So with all four cores under heavy load, the Turbo speed is 3600MHz. With two cores under heavy load, the Turbo speed is 3800MHz. But once the standard Turbo time limit expires (a few seconds), the processor will run at its base clock, which in your case is 3500MHz. This is normal behavior for Intel Turbo 2.0 Boost.

It is a common misconception that the maximum Turbo speed of a processor applies to all of its cores at the same time. In reality, it only applies to one core, for standard/default UEFI/BIOS settings of all the options related to Turbo.

Why you get all cores at 3900MHz, is from the Multi Core Enhancement option being enabled. The description of this option from the manual:

Improve the system's performance by forcing the CPU to perform the highest
frequency on all CPU cores simultaneously. Disable to reduce power consumption .

Multi Core Enhancement is a simple, automatic semi-over clock. It sets all the Per Core entries to 39, and sets the Turbo Time Limit to infinite. This option is enabled by default.

We can also OC the CPU manually on all cores to 3900MHz, but you said you were using the UEFI defaults, so the 3900MHz speed on all cores must be from Multi Core Enhancement.

In your case, using the XMP profile seems to have the side affect of disabling Multi Core Enhancement. One option setting changing another option setting can happen for various reasons. You can easily verify that with Load XMP Setting set to Auto, and then set to the XMP option setting. Either Multi Core Enhancement will be set to Disabled, or this option can disappear from the CPU Configuration screen. When over clocking using the All Core option, Multi Core Enhancement will be removed.

In you case, since your board is not a heavy duty over clocking board, using XMP might remove Multi Core Enhancement to reduce stress on the CPU VRMs.

You lost me on this statement: Someone suggested I try increasing the memory of the RAM. Just a typo I imagine.

Yes, XMP will increase the DRAM voltage automatically, or at least it usually does.

Multi-Core Enhancement is a simple, automatic semi-over clock. It sets all the Per Core entries to 39, and sets the Turbo Time Limit to infinite. This option is enabled by default.

I am I right in thinking that at bios default the max turbo is dependent on the number of cores used, I.E. 1 core =3900 and 4 cores =3600 each core.  Now with the Multi-Core Enhancement set to per core 39 would the processor be set to 3500/3900 and the turbo boost of 3900 would effect for all 4 cores? Also how long should the turbo boost stay at 3900 before down clocking to 3500.


Edited by bertybassett - 25 Aug 2016 at 1:46am