Showing results for 
Search instead for 
Did you mean: 

PCIE 4.0 x16 vs x8 RTX 3090

Level 8
Hi all,

I recently built my dream no-compromises PC, but I've run into a problem. One of the games I want to run is Fallout 4, which crashes constantly on my RTX 3090, but not with my GTX 1080Ti.

It looks like this being caused by NVFlex, if I understand correctly this is a library that allows for a game to take advantage of physX which is not implemented correctly to work with RTX cards. The only solution is to either turn the feature off or install a non-RTX gpu into another PCIE slot and slave it to the main GPU as a physX processor.

The motherboard I have is the ROG Maximus Z690 Extreme with two PCIE 5.0 x16 slots (RTX 3090 is a PCIE 4.0 card, so they run in 4.0), but they can only run in x8 mode if both are populated. Is downgrading my RTX3090 slot to x8 going to cause a bandwith issue and hurt performance? Do any z690 motherboards exist with PCIE 4.0 slots that can both run in x16 mode simultaneously?

I'm a bit torn on what to do here, I really enjoyed the NVFlex feature on my 1080Ti, really would be a shame to lose it, but I really like my performance in other modern games such as Halo Infinite, and don't want to lose that either,

Advice would be appreciated,