Dear FI,
The support of BPTA-VGDSAL-BK is compatible with 3090 series, only one card and water block can be. And the 16 riser flexible cable of BPTA-VGDSAL-BK is not compatible with 3090 series. Sorry where is the 2.75 slots wide you meant? Will you install the card with the original fan or with a water block?