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PCIE 5.0 optimum Config

Iam74Gibson
Level 7

The more I research this, the more confusing it becomes, so I will just give my scenario and hopefully someone can answer..

I just bought a Strix z790-E Gaming Wifi II motherboard. It has a PCIE 5.0 slot, and a M2 PCIE 5.0. The manual says if you use the M2 Slot, the lanes will be cut from 16 to 8 On the PCIE slot... 

I have a Strix RTX 4090 OC GPU... Gen 4 (they all are for now) If I buy a PCIE 5.0 NVME , and install my OS on it, using the M2 5.0 Slot, Will it degrade my GPU performance? I understand the lanes will reduce, but considering the GPU is Gen 4 in a Gen 5 slot, will it matter? Or, if I use my current Gen 4 Samsung Pro NVME, will it have the same effect on the GPU?  I have seen videos that say to make sure you use the correct M2 slot for the OS.....well? Which is the correct slot? Any advice is appreciated.

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1 REPLY 1

Jiaszzz_ROG
Customer Service Agent

Hello, @Iam74Gibson 

Due to the ongoing local holidays in our area, my response time may experience delays.
I apologize for any inconvenience the delayed replies may have caused.

According to the ROG STRIX Z790-E GAMING WIFI II manual, PCIEX16 (G5) and M.2_1 share the same lane.
When both slots are in use, PCIEX16 (G5) will operate at X8 bandwidth.


This might reduce GPU performance, but since both slots are CPU-provided, the actual performance impact depends on your CPU.
Additionally, the impact varies based on your workload, system configuration, and PSU specifications.

Thank you.

sharing complete hardware info & software config details will help us better understand the issue 🙂