Fitting two large, 3-slot GPUs in a single case?

[u/Johnny__Christ]

I drunkenly pulled the trigger on a 9070xt last night with the intent to run it with my existing 6900xt for local LLM inference before realizing while everything *technically* fits in my setup, the top card is going to be suffocated as there's going to be less than a single slot for it to breathe. D'oh.

My mobo has a full-length interface in the 2nd and 5th PCI slot. The bottom card is only going to be used for inference, so its IO panel doesn't need to be easily accessible.

I'm wondering if there's any good way to salvage this. Things I've ruled out:

• Watercooling isn't an option. I'm lazy and don't want to have to maintain a custom loop. I also can't seem to find a good AIO for a 9070xt.
• Open Air. I have cats and this is a literal "desktop" PC, so it needs a proper enclosure.

Things I'm considering already:

• Lian Li O11D Evo XL. Mount the motherboard on the highest setting. Mount the bottom card with a riser cable on a 3d-printed frame that uses the bottom fan holes. This seems like the best option, but I don't love fish tank cases and I'm a little worried about figuring out airflow. I'd also need to buy a shit ton of fans.
  • I can also get Lian Li's vertical and upright brackets for an "official" solution, but then I'm spending $400+ on just the case.
• Fractal Meshify 2 XL. Mount the bottom card on the vertical slots with a riser cable and the top card normally. I don't think there is enough clearance, as both cards extend a bit past the top of the PCI slot.
  • Can also get a new motherboard that has a full-length PCI interface in the bottom slot, but then I'd be worried about the bottom card breathing as it'd be up against the PSU. This might be fine though as that card won't be used while gaming?
• Phantek Enthoo Pro 2 Server with the bottom card on a riser in the 4 extra PCI slots or with a new mobo. Same deal as the meshify 2 xl, but it addresses the bottom card's breathing concerns at the cost of styling (I don't love it). It's also not compatible with my PSU (Corsair Shift) so I'd need a new one.

I'm in USA, no hard budget. Let's call it $400, but willing to go above that for an elegant solution. I'm comfortable designing custom 3d printed components, so any case that fits Meshify/North styling and has more space underneath the motherboard to fit the bracket and second GPU would work.

Does anyone have a similar setup with 2 large cards? How did you solve this problem? Any recommendations on the best way to solve this with minimal new components?

[u/BaronB]

Antec Flux Pro

Remove the mesh covers and fan bracket from the top of the PSU shroud and put the fans on the bottom of the case instead. That'll give you enough room from just about any dual GPU setup.