Power cycle system after turning off the CMS in BIOS
Power cycle system after turning off the CMS in BIOS
The riser model 4 should function properly at those velocities, so there shouldn't be a problem.
I'll consider trying it out the next day to swap your gen4 riser for a gen3 one, then adjust the PCIE settings to PCIE 4 and revert to the gen4 riser. Would you like me to confirm if that sounds good?
There have been several people facing the same problem recently, though I don't remember any discussions involving your type of equipment working. Some encountered issues with the GPU VBIOS not running when CSM was off, requiring a temporary replacement card to access the BIOS and re-enable it. Those were older models, so 30-series chips should work fine now.