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Question several questions related to alternative GPU placement

Jun 25, 2020
In order to keep temps low on my new GPU (Radeon VII), I intend adding a dedicated heatsink to it (Raijintek Morpheus II Core) and 2 120mm PWM fans underneath. That obviously makes the whole a bit bulky (at least 4 PCIe slots at the back of the case) and I wish to be able to use the other PCIe slots on my mobo (ROG CROSSHAIR VIII HERO (WI-FI)).
I first thought of doing a vertical mount, but that will kinda choke the airflow, as it's going to be very close to the glass side pane of the case.
So I'm pondering on this not-so-orthodox solution as to fix the whole (GPU+heatsink+fans) directly on the bottom part of the case, as it's vented (Lian Li 011D Dynamic XL).
My questions are the following :

1. PCIe raiser cable
I'll obviously need one. As the mobo supports PCIe gen.4, I'd like one that's gen.4 compatible and that's long enough so I can have it go over the other PCIe cards I wish to plug in the mobo.
Found the following one : PCIE4EXT11SS-040-v2
  • could that do the job ?
  • any alternatives (maybe cheaper?)
  • in my case scenario, does the angle of the cable matter ? Don't understand the importance of the cable being straight, left angle downward or right angle upward...
2. horizontal GPU mount ?
There's vertical ones for sure, but would there be some rigid frame on the market that could fit my user case scenario ? Basically, it's just the pins of the fans in the bottom of the case that holds everything in place, and that's a bit flimsy...

3. 120mm fan clips ?
Anything standard on the market that'd allow me to clip the fans to the Morpheus heatsink ? If not, I'll just go with Velcro strips or similar solution.

4. plug the fans in the GPU ?
This ought to be possible if I understood wright. I'd need :
- GELID PWM Fan Adaptor for VGA Cooler Fan (CA-PWM-02)
- a PWM Y cable
Is this correct ? I guess the Radeon VII has a 4 pin PWM fan header ?
Can I still somehow control the speeds of these fans or would I be better off plugging these in my fan hub (THERMALTAKE COMMANDAR FP) I'm gonna use for the case fans ?

5. thermal pad + copper heatsinks on top side of GPU pcb ?
ok, as this is my first build, I simply don't know whether the reverse side of the pcb card of the GPU also heats or not... If this is the case, would it be a good idea to cover it with thermal pads and to stick of these copper fan heat sinks to it, like these :

6. better to use 3x80mm fans (like the NF-A8 PWM) instead of 2x120mm ones ?
maybe gives more coverage of the pcb ?
The following thread (a bit dated I guess) does have some critical thoughts :
  • about 2x120mm fans
  • about potential overload of current draw from the GPU
  • about pulling config would be better than pushing one
Thanks for bearing with my lengthy post and appreciate all feedback and ideas !
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