New build - M.2_1 used and 8x vs 16x on PCIe_1

Discussion in 'Videocards - AMD Radeon' started by loquefxp, Oct 13, 2020.

  1. loquefxp

    loquefxp Member Guru

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    GPU:
    AMD Nitro 5500XT 8G
    Hey all, it's been a while (7-8 years). Apologies if this isn't the correct section.

    I've just put together a new PC. Asus Rog Hero, 5500XT with an M.2 SSD in slot one. I noticed in GPUZ that my GFX card appears running in 8x lanes even though it's in the first PCIe 16x slot on my motherboard.

    I checked the motherboard manual and it looks like using the M.2_1 slot for an SSD will downgrade the first PCIe slot for my GPU from 16x to 8x as they are sharing the CPU.

    I saw a couple of vids from like 2 years ago showing that 16x vs 8x PCIe 3.0 only had a 1% performance difference on FPS, is this correct for the modern GPUs such as my 5500XT or did I make a mistake installing an Nvme hard drive instead of going with a more conventional solid state drive like a WD Raptor or SATA SSD to ensure my GPU is running 16x?

    It's been a while, still catching up with recent tech. Appreciate any replies. Thanks.
     
  2. z8373767

    z8373767 Master Guru

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    GPU:
    Fury Nitro 1070/600
    It's weird for me. Using M2 storage turning off latest SATA usually. What mobo you have?

    EDIT: Nevermind. I know it's ASUS Z490 R Maximus Hero.

    About your question with PCIe 3.0 x8. Those tests are tricky imo.

    For a while i overclocked my Xeon via BCLK, PCIe drop from 3.0 x16 to 2.0 x16. I didn't notice any difference at all in benchmarks or several games like Valorant, CS:GO, Assassin's Creed IV, GTA V etc, but one game was really sensitive. Death Stranding. My FPS was good, but frametime and stuttering was terrible. I made almost 20hours in-game with that experience. I thought it was bad DX12 implementation. Good for me i was curious about DRAM Overclock and crashed my PC. I run Death Stranding on default with GPU running on PCIe 3.0 x16. Game runs like butter. I checked it twice. PCIe 3.0 x16 runs just better.

    I heard Horizon: Zero Dawn is also sensitive for PCIe mode. Maybe it's Decima Engine issue. https://www.reddit.com/r/hardware/comments/i46qtf/horizon_zero_dawn_on_pc_shows_significant/
    EDIT2:
    I found info on Asus site:
    "When M.2_1 is operating in SATA mode, SATA6G_2 will be disabled."
    also other M2 slots should affect PCIEX16_3, not 16_1
    Something's wrong here.

    EDIT3:

    I know what is wrong. It's "feature" of this GPU. The 5500 XT is wired as a PCIe 4.0 x8 card (physical tab is x16), that's why it runs PCIe 3.0 x8 on your mobo. I never heard about that before.
    https://www.tomshardware.com/news/amd-rx-5500-xt-vram-pcie-4
     
    Last edited: Oct 13, 2020
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  3. The Goose

    The Goose Ancient Guru

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    GPU:
    MSIrtx3070 gaming X
    Depending on what lanes your cpu supplies you should get x16 on the gpu unless pci 1 and m.2 1 share with sata ports 1_2, if your running sata drives aswell try them on chipset fed lanes, im running an Asus Prime x570 with a Ryzen 7 3800x with 2 nvme drive and 2 sata drives, my sata drives are on ports 3-4 so i get x16 on my gpu and x4 on both my m.2 ports.
     
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  4. loquefxp

    loquefxp Member Guru

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    GPU:
    AMD Nitro 5500XT 8G
    Appreciate the replies thank you Goose and Z8.
     
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