New build, Asus Maximus Z790 Dark Hero motherboard. There is one PCIe 16 slot shared with and an M.2_1 slot connected to the CPU. If I mount the GPU alone I’m supposed to be able access the full 16 lanes. However, if I mount an M.2 SSD in the M.2_1 slot, it will shares the lanes with the GPU so both slots will operate at x8 speeds.
Since I fly primarily using VR, I would like to know if anyone has experience with the impact to performance when running a 4090 at x8 speeds vs x16 speeds. I’ve been able to find information online indicating x8 speeds result in just a few % difference in performance for gaming in general. Not able to find any information regarding performance specific to MSFS or VR specifically. My plan was to mount a 4tb SSD in the M.2_1 slot unless GPU is dramatically impacted at x8 speeds. Thanks in advance!
Put two (pick your size) gen 4 m.2’s on a pair of the chipset m.2 slots in RAID0. That’ll give you x16 on the GPU (if you want it badly enough) and you’ll have a super-fast SSD drive for FS2020, etc.
The downside is it’s RAID0. But all I have is FS2020 and XP12 on mine so if it goes belly up, no biggie.
That’s how I get my x16 GPU fix (placebo or not 
) and a VERY quick drive.
If your disk is not a Gen.5 then you can install it in one of the Gen.4 M.2 slots without performance loss.
If your disk is a Gen.5 then you can still install it in the Gen.4 M.2 slots without noticeable performance loss. MSFS won’t benefit from Gen.5 throughput, and neither will most programs we use daily. Marketing loves the Gen.5 big numbers but they don’t translate to real world scenarios.
I have two new 990 Pro’s, one 2tb and one 4tb, both Gen 4. I think I’ll install the 4tb in the M.2_1 slot (OS and applications) and put the video card in the CPU controlled PCIe x16 slot, understanding it will run at x8 speeds. From what I’ve read, a 4090 running at x8 will not over saturate the available lanes. I’ll put the 2tb in the M.2_2 slot for my community folder and file storage. While the risk of SSD failure is low, I’m just not conscientious enough to manage timely backups from a RAID0 configuration. Thanks for the recommendations!
In this case you can simply install them in M2_2 and M2_3 slots leaving M2_1 empty. No performance loss.
I’ll give that a shot. The M.2_2 is controlled by the CPU so that will work for the OS drive. The M.2_3 is controlled by the chipset but performance should be acceptable for storage. Thanks again!
There’s isn’t any noticeable performance difference between the two, the link between the chipset and CPU is twice as fast as the drive itself (equivalent to PCIe 4.0 x8).
Good to know!