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Asus Maximus Hero z790 & Samsung m.2 990 Pro is slower than expected

Level 7


I'm new  here and I would like to say hello to everybody!

I'm building my new rig and I have a problem with my m.2 that is slower than expected...

Here is my setup :

  • Motherboard : Maximus Hero z790
  • Gpu : MSI 4080 suprim X
  • CPU : i7 14700
  • RAM : DDR 5 Corsair 48 Gb
  • M.2 : 990 Pro 2 Tb
  • BIOS : 1501

So, normaly the 990 Pro is suposed to read @ about 7450 Mb/s and mine is stuck @ 7000 Mb/s, is it normal?

I've tested it with the Samsung Magician software. I've tried with normal and full power settings.

More info : The GPU is in the first PCIe slot and the m.2 is also in the first M.2_1 slot (the closest one to the CPU).

Thank you for your help!


Level 7

I too am experiencing slower performance than expected, using Samsung Magician and UserBenchmark to evaluate. 

To make matters worse, when I updated the SSD firmware to the latest it actually slowed the drive down further.  On firmware 3B2QJXD7 it averaged around ~6900/6500.  After the update, it now averages around ~6700/6100 read/write respectively.  You can see the reduction in speed in the attached image.  This is considerably less than I would have expected.  This is my setup:

  • Motherboard: Asus Rog STRIX Z790-E Gaming WIFI
  • GPU: MSI GEForce RTX 4070
  • CPU: I9-13900K
  • RAM: DDR5 Corsair Vengeance 64GB (4x16GB) 6600MHz C32-39-39-76
  •  M.2: 990 Pro 1TB, Firmware Version: Latest (4B2QJXD7)
  • BIOS 1501
  • Windows 11 Home If anyone knows any tips or tricks to get better performance from 990 Pro on Asus Z790 models please pass along.  Benchmark images below.  Thanks Screenshot 2024-01-08 131110.pngScreenshot 2024-01-08 143021.png 

@murphyben Uh, I don't know if it matters to your situation with the SSD since I haven't looked into potential bottlenecks that much, but the maximum # of channels that your CPU supports is only 2. Meaning your 4x16 RAM sticks aren't really supported properly by your CPU, and that can negatively affect at the very least your RAM performance. But yeah, I don't know if it affects your SSD situation though, but if you're also making your SSD and GPU share the same PCIe slot (which @Actarus500 did) then I'd suggest changing the m.2 slot for your SSD.

I'm not gonna source anything because I haven't made it a point to remember where I read stuff in all of my recent researching done for my own build, but feel free to look up these things on your own. I just figured any kind of help is better than no help at all.

Thanks @PoorlyCreative .  I installed HWiNFO64 and sure enough my m.2 and GPU were sharing the same spot.   

Taking the m.2 off the shared PCI slot made a significant difference in m.2 performance, which is funny, because it was actually cutting into the GPU bandwidth (and in theory) keeping the m2. speed.  New info, with m2. no longer sharing:


Appreciate your help.  Although I had read it before, took me posting here and hearing one more time to install HWiNFO64 and see it for myself.  Ben


Level 8

@Actarus500 I'm recently getting into this whole "build your own computer"-scene (currently acquiring parts for mostly a asus rog x evangelion-02 build with 14900kf, asus rog thor 1600w and rgb fans to replace the ones included in the case), but I was reading about that PCIe slot you're using for your GPU and the m.2 slot you're using that shares it, and according to what I read about it, it cuts down the performance by having them share the same PCIe slot. (Although the ones talking about it were talking about how it cuts the GPU's performance by doing that, but I'd assume it has a similar effect on the SSD as well, since the PCIe slot doesn't seem to be intended to support both a GPU and an SSD without a drop in performance.)

So I'd assume you're better off not using that m.2 slot, and see if it improves the performance. I'm sorry I couldn't provide better help or source it, but I've been going hardcore researching about this stuff and the places where I read it is kind of a low priority for me while doing all this all at once. But you can of course research it yourself if you wish.

Super Moderator

Hi @Actarus500,

I don't see an issue with the performance you're seeing. The peak numbers aren't always going to be hit depending on several factors including the workload. Have you tried Crystal Bench?

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090