CPU PCIe config and M.2_2

[Loxnar]

I have a ROG STRIX Z590-E Gaming Series, with WiFi 6E motherboard and I am trying to utilize the M.2_2 hard drive slot. In order for the system to recognize the hard drive I have to go into BIOS and advanced>onboard device configuration>CPU PCIE Configuration Mode and change it to "PCIEx16_1 + PCIEx16_2 + M.2_2"

My question is am I choking the PCI lanes for the graphics card by doing this? I have 3 SSDs in this tower (not utilizing M.2_1) but I could easily remove one drive if it means I am indeed splitting the PCI lanes between the hard drive and my graphics card.

Other info that may be of use:
CPU: Intel Core i9 10850K
GPU: ASUS ROG STRIX GeForce RTX 3080
SSD in slot M.2_2: SAMSUNG 980 PRO M.2 2280 1TB PCI-Express Gen 4.0 x4, NVMe 1.3
M.2_3 SSD:1TB Intel 660P M.2
M.2_4 SSD: ADATA XPG SX8200 Pro 2TB Gen3x4 PCIe M.2 2280

The intel is the one with the boot system on it and the one that came with the rig (yes i bought prebuilt only way to get a 3080 these days), but i could easily make the samsung the boot drive and the ADATA my gaming drive.

[Zeroed85]

M.2_2 for some reason shares lanes with the CPU. So if you populate M.2_2 it will run the PCIEX16_1 slot in 8x. If you dig through the manual it will state this. I don't really understand why Asus have chose to have the M.2_2 sharing lanes with the CPU and not the chipset though...

[autosellers]

Activate HYPER M.2 X16 and Enable under CPU PCIE Configuration Mode (ADVANCED) tab

Restrictions

1. Update to latest BIOS before using RAID on CPU function.

2. For Z590, Z490, Z390 and Z370 series motherboard, install IRST version 16 or above to use RAID on CPU function. Only Intel SSDs can active Intel RAID on CPU function in Intel platform.

Install one HYPER M.2x16 card in second PCI slot (CPU Controlled)
Install up to four SSD cards

Put on your speed helmet and enjoy.

[Grimpak]

M.2_2 for some reason shares lanes with the CPU. So if you populate M.2_2 it will run the PCIEX16_1 slot in 8x. If you dig through the manual it will state this. I don't really understand why Asus have chose to have the M.2_2 sharing lanes with the CPU and not the chipset though...

4 nvme slots. also 10th gen doesn't have the same pcie lanes as 11th (16 vs 20), meaning any nvme connected directly to the cpu will need to share with the gpu lanes.

putting the m.2_2 on the chipset would limit even further the number of bandwith available for the IO.

[rolldog]

I'm running the APEX XIII Z590 with an i9-11900kf, and since I have a watercooled 3080 Ti, I put a Samsung 980 Pro in M.2_1, left M.2_2 empty, and added 2 more M.2 SSDs using the DIMM that was provided. From my understanding once the M.2_2 slot is used, PCIEX_16_1 drops to x8. I'd rather have my other SSDs running slower than taking bandwidth from my 3080 Ti

[randomdud3213]

I'm running the APEX XIII Z590 with an i9-11900kf, and since I have a watercooled 3080 Ti, I put a Samsung 980 Pro in M.2_1, left M.2_2 empty, and added 2 more M.2 SSDs using the DIMM that was provided. From my understanding once the M.2_2 slot is used, PCIEX_16_1 drops to x8. I'd rather have my other SSDs running slower than taking bandwidth from my 3080 Ti

I kind of wish I knew this when I bought the mobo a while back. I'm running a 10th gen CPU with m.2 drives in slot 2 & 3. Not only is my GPU only able to run at X8 speeds, but my boot SSD that's in m.2_2 is running at X1 speeds, but m.2_3 is fine at X4.

Eventually I'll end up moving both ssd's down a slot to hopefully fix the GPU speed, and my boot ssd running at X1.

[Exalix]

I know this sounds very easy to say; but sell your 10th gen cpu if you can, and buy a 11th gen cpu. The Z590 motherboard is clearly made with 11th gen cpu in mind for optimal nvme/pcie lanes across the board and crippled with a 10th gpu. Sad but true.

[Grimpak]

I know this sounds very easy to say; but sell your 10th gen cpu if you can, and buy a 11th gen cpu. The Z590 motherboard is clearly made with 11th gen cpu in mind for optimal nvme/pcie lanes across the board and crippled with a 10th gpu. Sad but true.

well, he has a 10850k, so any change will be at most a sidegrade, at worst a downgrade.

[nailmaker]

yeah move the drive out of the m.2_2 spot as this is putting your graphics card at x8.. and if you have four slots and move it to m.2_4 then you lose sata ports.. dont know if that board has 4.. my maximus hero xiii z590 board has 4 slots and you cant use _1 unless using a 11th gen cpu... and also cant use m.2_2 as it brings the x16 down to x8... im telling ya.. they advertise all it has but dont tell you that if you use them all then it just starts downgrading itself and stuff stops working.. lol.. move your stuff off that drive in the m.2_2 over to a sata ssd and just leave the one m.2 in there. will run just as fast.

[G\'David]

I know this sounds very easy to say; but sell your 10th gen cpu if you can, and buy a 11th gen cpu. The Z590 motherboard is clearly made with 11th gen cpu in mind for optimal nvme/pcie lanes across the board and crippled with a 10th gpu. Sad but true.

I'm with you on that for sure. 11th Gen gives more pci lane access and the idea of running a 10th gen CPU on an 11th Gen board hardly makes sense.
I opted for the 11600kf as the thermals were better and the core speeds too. Six physical cores are more than enough for my needs and I love to see that without any tweaking these cores are at 4.9