[SOLVED] ram memory performance drop with 3700x

[JayGau]

Hi Guys,

I just installed my new Ryzen 3700x and I am pretty happy about it but I have a concern. With my 2700x my RAM was benching 102% on UserBenchmark but with the new CPU I get only 85%. All the numbers are worse (read, write, latency). I did a bios update after I installed the cpu but I don't see how it could lower the ram performance. By the way I set back the ram clock to 3133 MHz like it was before so it's not that. Is it really the new CPU that makes the RAM performing less good than before? I was expecting the opposite.

My specs are:

Thermaltake Versa N21 Onyx Edition case
ASUS ROG Crosshair VII Hero
AMD Ryzen 3700x
NZXT Kraken X52 cooler
2x8 Gb Corsair Vengeance LPX DDR4 3000 C16
Samsung 970 EVO Plus - 1TB PCIe NVMe - M.2 Internal SSD (system drive)
Seagate Barracuda 2TB ST2000DM008 (backup drive)
Gigabyte GTX 1080
Corsair CX650 PSU

Thanks in advance!

 

[Karadjgne]

How so worse?

You do understand that user benchmark is a comparison to others with the same ram and same cpu etc right? So compared to other ppl running a 2700x you are 102%. Compared to ppl running a 3700x, your ram compares at 85%, meaning those ppl are pushing their ram to the limits while you aren't. Ppl in the 86-102 bracket are running tighter timings, OC speeds etc.

Your ram hasn't changed, only the comparison base. Think of it this way, in 8th grade you might have been the tallest kid in school, your comparison base is a bunch of 6,7,8th graders. Go to high school, 9th grade, you are short compared to the Seniors.

 

[JayGau]

I am not sure UserBenchmark compares ram scores with people with the same CPU. I thought the components were compared with the same components separatly, not by combination. For example my GPU is getting the same percentile than before and for some reason my NVMe is getting a higher score (maybe because of the bios update I don't know).

Anyway, I didn't rely only on the relative score. As I said not only the percentage is lower but the absolute numbers too:

multi-core: 37.2 GB/s -> 28.9 GB/s, single-core: 30.8 GB/s -> 26.8 GB/s, latency: 74.3ns -> 76.9 ns.

So something is lowering down my ram speed and the only thing I changed is the CPU.

 

[CountMike]

Check Infinity Fabric (FCLK) frequency, should be set same as RAM base frequency. That's half of your 3133MHz. At higher frequencies it matters a lot, if not 1:1, memory latency goes higher, lowering RAM score and performance. DOCP should set it automatically but if you are setting and overclocking memory manually FCLK will be wrong.

 

[Dragzor]

New Ryzens up to a 8core memory write speed is half of 2x00. 3900x is without this problem.

Memory latency is generally worse then 2x00. But now ur more likely to get higher frequencies and FCLK.

For ramspeed 3200 or worse, it's usually beneficial to up the FCLK to max u can get- so like 1800/1900. U'll get better bandwidth with minimal loss of latency. With 3400+ its better to couple/tie RAM with FLCK. (Its usually done by auto settings)

 

[JayGau]

Following your comments I tried to play with the FCLK. I put half of 3133 (so 1567): no improvment at all. I tried to go higher like 1900 but my lantency actually went up, so no gain overall. Higher than that the computer doesn't even boot.

But I searched a little bit more online and Dragzor is right. It seems that the third Ryzen generation chips have some difficulty with low speed memory. AMD themselve recommand 3600MHz to acheive optimal RAM and CPU perfomance for the 3700x. So I ordered a G.Skill 3600 C16 kit and I will sell my 3000 one.

EDIT:

I received the G.Skill 3600 C16 kit two days ago and I returned it because for some reason my 260$ motherboard cannot run it at full speed and timing. The best I could do was 3333 MHz at 16-16-16-36. I am not going to pay 280$ for RAM that cannot work at its advertised specs. I ordered a 3200 C14 kit instead and that should run with the default D.O.C.P. profile and give me some performance boost compared to my 3000 C16. Also Asus just released a new BIOS update and maybe it will help with this memory performance issue.