memtest86 () Measuring CPU/cache/mem speed (cpu_cache_speed) discrepancy

[ivaylodj]

Dear memtest86 team,

Recently I bought a new DDR4 memory kit, a Corsair DDR4 3200 Mhz 2x32GB 64GB kit, for my most recent home machine built 02.2020. The 'old' DDR4 memory kit, Kingston HyperX Fury DDR4 2666 Mhz 2x16GB 32GB kit, was 'moved' to my 'old' home machine built 06.2018, where such a 32GB kit was already present.

The short specs of the machines are as follows (more details in the attached log files):

The 'new' machine - CPU: i9-9900K, Z390 based mini-ITX form factor (2x ram slots) mainboard, 2 x 32GB in all (two) mainboard slots.
The 'old' machine - CPU: i7-8700K, Z370 based ATX form factor (4x ram slots) mainboard , 4 x 16GB in all (four) mainboard slots.

For my big surprise the detected memory access speeds for CPU L1, L2, L3 and DDR ram memory (including detected memory latency) are much worse on the 'new' machine compared to the 'old' one.

The 'old' machine:
2020-04-09 21:38:57 - cpu_cache_speed - (Attempt 3) clock cycle (ms): 3697111
2020-04-09 21:38:58 - cpu_cache_speed - Using average of last 3 samples (3697111, 3697202, 3697111)
2020-04-09 21:38:58 - cpu_cache_speed - CPU speed: 3697.1MHz
2020-04-09 21:38:58 - cpu_cache_speed - measuring L1 cache speed at 0x89282000 (32 KB)
2020-04-09 21:38:58 - cpu_cache_speed - L1 cache speed: 225618 MB/s
2020-04-09 21:38:58 - cpu_cache_speed - measuring L2 cache speed at 0x8924A000 (256 KB)
2020-04-09 21:38:58 - cpu_cache_speed - L2 cache speed: 106452 MB/s
2020-04-09 21:38:58 - cpu_cache_speed - measuring L3 cache speed at 0x87591000 (12288 KB)
2020-04-09 21:38:58 - cpu_cache_speed - L3 cache speed: 45194 MB/s
2020-04-09 21:38:58 - get_mem_speed - measuring mem speed at 0x7C559000 (100864 KB)
2020-04-09 21:38:58 - get_mem_speed - mem speed: 25512 MB/s
2020-04-09 21:38:59 - cpu_cache_speed - Memory latency: 20.186 ns
2020-04-09 21:38:59 - Retrieving CPU MSR data
2020-04-09 21:38:59 - GetIntelArchitectureSpecificMSRInfo - CPU Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz: 6.158

vs The 'new' machine:
2020-04-10 05:55:18 - cpu_cache_speed - (Attempt 3) clock cycle (ms): 3645450
2020-04-10 05:55:18 - cpu_cache_speed - Using average of last 3 samples (3645450, 3645369, 3645546)
2020-04-10 05:55:18 - cpu_cache_speed - CPU speed: 3645.4MHz
2020-04-10 05:55:18 - cpu_cache_speed - measuring L1 cache speed at 0x84E41000 (32 KB)
2020-04-10 05:55:18 - cpu_cache_speed - L1 cache speed: 191041 MB/s
2020-04-10 05:55:18 - cpu_cache_speed - measuring L2 cache speed at 0x84E09000 (256 KB)
2020-04-10 05:55:18 - cpu_cache_speed - L2 cache speed: 87991 MB/s
2020-04-10 05:55:18 - cpu_cache_speed - measuring L3 cache speed at 0x8361A000 (16384 KB)
2020-04-10 05:55:19 - cpu_cache_speed - L3 cache speed: 44826 MB/s
2020-04-10 05:55:19 - get_mem_speed - measuring mem speed at 0x676A4000 (133632 KB)
2020-04-10 05:55:19 - get_mem_speed - mem speed: 20767 MB/s
2020-04-10 05:55:20 - cpu_cache_speed - Memory latency: 22.281 ns
2020-04-10 05:55:20 - Retrieving CPU MSR data
2020-04-10 05:55:20 - GetIntelArchitectureSpecificMSRInfo - CPU Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz: 6.158

As seen above the L1 access speed difference is around 17%, the L2 difference is around 19%, the L3 difference is below 1% (only here almost identical speeds are detected) and RAM memory speed difference is around 21% (latency difference is around 10%).

What this big discrepancy is due to and why in favor of the inferior hardware machine? I'm really frustrated from the results of cpu_cache_speed.

PS: Please, find the memtest log files share here: https://drive.google.com/open?id=1mc...dQbuJiiMdzHbOF.

Best regards,
ivaylodj

[David (PassMark)]

The new i9-9900K has more cores but a lower single threaded clock speed than i7-8700K (3.7Ghz vs 3.6Ghz). So old hardware isn't inferior in all respects. So that will be part of the difference.

You might also want to check the BIOS settings on the new machines. Make sure you have XMP on.

Maybe the timings of the new 32GB RAM modules aren't as aggressive as the old 16GB modules?