Kaby Lake / Asrock disappointment, RAM weirdness

[Prime95]

I decided to try a Kaby Lake CPU. It is well documented that there are no architectural improvements, but it is clocked 200 MHz faster and supports DDR4-2400 vs. DDR4-2133.

My i5-7500 is here and I'm comparing it to an i5-6500. Benchmark numbers are for throughput on a 3584K FFT. Motherboard is from Asrock with support for non-Z ram OC. Exactly what non-Z OC is has never been explained.

First up, the i5-6500 with "sport+" ram OC: 203 iters/sec.

Next step is to upgrade the BIOS to support Kaby Lake. Testing the i5-6500 again: 200 iters/sec. That's annoying - the new BIOS is slower.

Next up Kaby Lake with no ram OC, DDR4-2400: 189 iters/sec. Ewww.

Now Kaby Lake with "sport+" ram OC, DDR4-2400: 195 iters/sec.

And Kaby Lake with "sport+" ram OC, DDR4-2133: 204 iters/sec.

Finally, Kaby Lake with "sport+" ram OC, DDR4-2266: 185 iters/sec.

Next I tried my best Ram sticks (DDR4-3200) vs. the cheapo DDR4-2400 ram tested above. No difference.

Conclusion: If you are using Asrock motherboards with SkyLake you can expect maybe a 0.5% performance boost upgrading to Kaby Lake.

Weirdness: Why does setting ram to DDR4-2400 or DDR4-2266 give worse performance than a DDR4-2133 setting??

Extra credit: Can anyone make an educated guess as to what Asrock's non-Z ram OC does?

[henryzz]

How do temperatures compare between the two chips?

[Prime95]

Originally Posted by henryzz

How do temperatures compare between the two chips?

Roughly the same. Kaby runs undervolted by 30mV and its at 60C. I have 3 SkyLakes undervolted by 35mV and they average 60C (55C to 64C).

[mackerel]

Is it possible to monitor the ram speed/timings while in OS?

[Prime95]

Originally Posted by mackerel

Is it possible to monitor the ram speed/timings while in OS?

I know little about available Linux tools

[Mark Rose]

Michael at Phoronix has been posting about getting poor performance with Kabylake with the P-state scheduler.

I've been meaning to experiment with Intel's Clear Linux distribution as it is optimized for Haswell and newer.

[Prime95]

Originally Posted by Mark Rose

Michael at Phoronix has been posting about getting poor performance with Kabylake with the P-state scheduler.

I think I've disabled P-state and C-state options in the BIOS. I'll double-check.

[Mark Rose]

Originally Posted by Prime95

I think I've disabled P-state and C-state options in the BIOS. I'll double-check.

The P-State scheduler is a kernel algorithm. Which distribution of Linux and kernel are you using? `lsb_release -a` and `uname -a` should give the answers to both.

https://wiki.archlinux.org/index.php...quency_scaling

[Prime95]

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 14.04.3 LTS
Release:	14.04
Codename:	trusty

Linux h110itx4 3.19.0-25-generic #26~14.04.1-Ubuntu SMP Fri Jul 24 21:16:20 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

[Mark Rose]

Originally Posted by Prime95

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 14.04.3 LTS
Release:	14.04
Codename:	trusty

Linux h110itx4 3.19.0-25-generic #26~14.04.1-Ubuntu SMP Fri Jul 24 21:16:20 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Alright, it's most likely not the issue then. The pstate governor isn't enabled by default in Ubuntu 14.04.

[J F]

Originally Posted by Prime95

Can anyone make an educated guess as to what Asrock's non-Z ram OC does?

If I remember this correctly: only the Z-series chipsets have
features that allow the user to change VCore, multipliers and
other stuff needed to over-/under- -clock/-volt K-processors.
Board manufacturers can put the 'missing parts' on their own
on their boards and alter firmware to offer that -> non-Z OC.
(non-Ks don't allow that regardless of chipset, except maybe
baseclock changes)

My guess for 'non-Z ram OC' is that on non-Z boards with non-K
processors, it allows at least memory OC.