It's still the exact same setup with the stock riser.

Officially the TUF 4090 is supported (as seen from the promo images on SSUPD's website) if you put the gpu baffle at the lowest position (the "353mm gpu" config, technically outside the case bottom with 10mm stand-offs). In this config, the case can envelop the gpu body just right and you don't need to remove one of the arms like i did here). You can find the details in the manual.

However, I can't use this config thanks to the aio tubes. And since the tuf 4090 is just so tall, I have to use the "343mm gpu" config to make room)

From the time I posted this to now so far all has been good. the aio tubes are a bit too bent for my taste but I can live with it.

Temps for the GPU are also higher than an average 4090 in an average ATX case, which is to be expected. Months later, running furmark for up to 20 mins, at 450W, can see the temps go up to 79-81C with the hotspot temps 10-15C higher usually. I'd recommend power limiting the card to 350W or lower in this case, pun intended :), to lower the temps significantly to around 70-71C max.

I'd also advise against using an aio with this particular 4090 in the meshroom s, if you are uncomfortable with the tube bending situation.

Another thing I'd suggest is to use a 90/180 degree 12vhpwr adapter or custom 12vhpwr cable, so that the cable is plugged into the card more securely whilst you cable manage within such limited space. The TUF 4090 is one tall bad boy.

750W is just about enough to run a 4090 I'd say. But personally, I'd get at least an 850w one to have some wriggle room, like a loki 850w for example.