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Low Cinebench Single Core Scores Due to Strange Core Ranking 3900XCore Ranking

Question asked by ltron on Dec 25, 2019
Latest reply on Dec 25, 2019 by hardcoregames™

I have a strange issue with my 3900X, on average the cores in the slow CCD 1 chiplet (4300-4400MHz) are ranked as faster in the CPU's firmware than the cores in the fast CCD 0 chiplet (4500-4650MHz). When applications are not using my fastest core 0 (correctly ranked) they will use a core pair that are ranked #2 and #3 fastest (incorrectly), these are cores 6 and 8 from the slow CCD 1 chiplet and they are only capable of 4.425GHz max which results in low Cinebench R15 and R20 single core scores of 205 and 510 respectively, multi core is fine at 3200 and 7250. Other people get 520-535 from what I've seen.

Here is a HWInfo screenshot and a Ryzen Master screenshot (attached) so you can see what I mean, in HWInfo the #numbers on the right are how the cores have been ranked in the factory and written into the firmware and the #numbers on the left are what Windows thinks the ranking is. Can you check this on your CPU, particularly those with low Cinebench scores?

I have confirmed this ranking in Linux too so it's not a Windows issue and all screenshots I've seen from other people have shown CCD 0 correctly ranked above CCD 1. I have confirmed that all cores in CCD 0 do at least 4500 MHz by disabling CCD 1 (which resulted in 521 in Cinebench R20 and 210 in R15) whereas all cores in CCD 1 do at most 4425 MHz. I think someone may have made a mistake in the factory and ranked the cores wrong. Is there a plausible explanation for this ranking being correct and does anyone else have this problem? I'm asking for educational purposes, not that I can fix it as that's up to AMD (hopefully they can fix it if I can determine the problem is not unique to me) and I certainly wouldn't RMA a CPU over this.

This CPU core ranking is replicated across both an MSI X570 ACE and a Gigabyte X570 Master and multiple BIOS versions and AGESAs. CPU-z is fine at 541 single core (it does its own thing and uses core 0 which is my fastest core so that's why it's not affected by the ranking) and Geekbench 5 is fine probably for the same reason and I get 1315 single core. I ran Aida 64 Memory Latency test which loads core 0 and gives me 4.6GHz+ so I could show the CPU is capable of these speeds in the screenshot.

My specs:
AMD R9 3900X
Gigabyte X570 Master
32GB Crucial Ballistix CAS 16 DDR 4 3600MHz
Noctua NH-D15S
Palit GTX 1080 Gamerock Premium
Corsair RMi 1000W PSU
Corsair MP510 960GB
Windows 10 1909 64bit Pro

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