I personally have a rear exhaust on mine cause I had an extra fan. You don't really need it all that much these days, especially with the coolers that 4090 comes with and 7800X3D running fairly chill and you already having 6 fans in the case with 3 of them being exhaust. But it wouldn't hurt.
On a side note, I actually have the exact same AIO and I'd suggest going into the settings and adjusting the pump speed to 70-80%. I read reviews in the past and if I remember correctly, they said there's basically little to no difference in AIO cooling performance once you go above 70% but the noise difference is big. Trust me on that cause the noise the pump makes at 100% is very annoying and distracting.
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850
