9900KF IMC Weak?

[Kitsan]

So my 9900KF is a strong overclocker in terms of CPU core clock but it's utterly abysmal at memory overclocking...… I wondered if it was the motherboard but my old 8700K is still able to run 4400mhz XMP, yet I can't even get my 9900KF to run at 3200mhz with very relaxed memory timings and standard core clocks....

 

Is there anything I should try before I return it as it has completed Cinebench at 5.2Ghz?

[Mira Yurizaki]

Intel's processors don't really benefit from having faster RAM than from what Intel recommends in most use-cases anyway. See https://www.techpowerup.com/review/intel-core-i7-8700k-coffee-lake-memory-performance-benchmark-analysis/10.html

[Princess Luna]

49 minutes ago, Mira Yurizaki said:

Intel's processors don't really benefit from having faster RAM than from what Intel recommends in most use-cases anyway.

Intel benefits plenty from memory, fine tuning timings alone already gives meaningful gains in performance.

 

I have noticed you always go around saying memory is meaningless for Intel which is not accurate since 2500k's days.

Both these videos should already give a good idea about the subject.

 

Also none you wrote really answers OP.

 

@remus243 Have in mind that the 9900KF does have a "broken" silicon to a degree, it's iGPU is disabled for a reason after all.

 

What voltages are you running the memory at? You mentioned having a 8700K, are you re-using your old windows install?

What's the best you managed on timings at 3200mhz?

[LukeSavenije]

18 minutes ago, Mira Yurizaki said:

Intel's processors don't really benefit from having faster RAM than from what Intel recommends in most use-cases anyway.

i see up to a 5% increase here though, and quite a difference in what speed and cl rating they used with the exact setups

https://www.tomshardware.com/reviews/best-ram-speed,5951-3.html

http://www.redgamingtech.com/testing-how-memory-speed-impacts-intel-fun-with-memory-configurations-on-z390/

 

as @Princess Luna said, there was a time it mattered a lot less than it currently does

[cried22]

56 minutes ago, remus243 said:

So my 9900KF is a strong overclocker in terms of CPU core clock but it's utterly abysmal at memory overclocking...… I wondered if it was the motherboard but my old 8700K is still able to run 4400mhz XMP, yet I can't even get my 9900KF to run at 3200mhz with very relaxed memory timings and standard core clocks....

 

Is there anything I should try before I return it as it has completed Cinebench at 5.2Ghz?

I was only able to get my 9900kf to 4100mhz on 4400mhz ram. On the other hand, I had to return my 9900ks because the ram wouldn't go above 2600.

[AnonymousGuy]

The IMC is only officially guaranteed to support 2666.  My 9900KF runs at 3600 but not the XMP 3866 of my memory kit.  I didn't care because RAM speed doesn't really matter and hasn't mattered for the last several years since DDR3-2133.

 

Also, memory support comes down to the BIOS (what sort of training is it doing on cold boot?), the motherboard (trace layout / isolation), and the kit.  It may not just be limited by the IMC.

 

Have you tried tweaking VCCIO and VCCSA to get a bit more stability?

[Kitsan]

I can confirm that memory speed does matter and does effect fps depending on the engine, so it is important to me as I play at 1080.

 

Well at least it's a known factor, this is the first cpu I've had with a poor IMC. I'll try to get it working at 2666 otherwise I guess in going to struggle to return it.

 

Thanks for the replies! 

[LukeSavenije]

26 minutes ago, remus243 said:

Thanks for the replies! 

you're welcome, you can mark the thread solved by pressing the checkmark on your left with the post that helped you most

[cried22]

Yeah ram speed really does matter

[Kitsan]

Oh jeez, so I thought to myself I need to know if it's the motherboard before I give up entirely on my 9900KF.

 

So I plugged in my old Z370DP D3 and so far i've got the 9900KF at 4.8ghz all core in Cinebench/3dmark (Haven't pushed it further as the VRM is beyond weak)

 

And the memory....

 

3866 16-16-16-36

 

It won't post any higher speed than that and I don't want to push the memory timings any further as the bench scores actually started to decrease.

 

I tried the Z390 with three kits of RAM and 9900KF on the latest Bios and those kits worked fine with my 8700K on XMP, so I contacted Gigabyte and asked for an RMA which they granted.

 

Joys of the PC master race....

 

 

[cried22]

2 hours ago, remus243 said:

Oh jeez, so I thought to myself I need to know if it's the motherboard before I give up entirely on my 9900KF.

 

So I plugged in my old Z370DP D3 and so far i've got the 9900KF at 4.8ghz all core in Cinebench/3dmark (Haven't pushed it further as the VRM is beyond weak)

 

And the memory....

 

3866 16-16-16-36

 

It won't post any higher speed than that and I don't want to push the memory timings any further as the bench scores actually started to decrease.

 

I tried the Z390 with three kits of RAM and 9900KF on the latest Bios and those kits worked fine with my 8700K on XMP, so I contacted Gigabyte and asked for an RMA which they granted.

 

Joys of the PC master race....

 

 

Wait wait wait...don;t your tests confirm its the IMC of the 9900kf if the higher speeds worked fine on the 8700k?

[Kitsan]

I have no idea, perhaps it's an intermittent fault such as a slightly bent motherboard pin?

It's not the 5.2GHz clock either as I tried the 9900KF at stock speeds too, I can't replicate it on my Z370P D3.

 

I'll post up the results of what the Gigabyte techs find but i'm not expecting to get my Z390 Master back until early Jan