I've been thinking about replacing the case on this machine for a while now and I just realised my top GPU was sitting at 80 while I was playing Dark Souls earlier so its really got me thinking it has to be done now

thats what it looks like inside my case right now. I have 2 120mm intakes in front and another 2 on the side, 1 200mm and 1 120 on the rear as outgoing air. My GPUs are MSI gaming Edition 290s. First problem is I ended up with a non modular psu. So thats a pain. However my plan was to buy a 540 air and some extensions so i can stick that psu in the back and only have the leads I need coming through. Then have 3 120mm fans in front and one in the rear. Now my CPU cooler Is doing a decent enough job I think its at 4.6 and sits around 60 but would an AIO water solution help to keep my GPUs cooler because theres less hot air being dumped into the case.
Whats the best course of action here that isnt a full waterloop as thats going to go far over budget. Ideally id like to be in the £300-£350 region to fix this.
It also needs a dust. Thats my job on saturday.

thats what it looks like inside my case right now. I have 2 120mm intakes in front and another 2 on the side, 1 200mm and 1 120 on the rear as outgoing air. My GPUs are MSI gaming Edition 290s. First problem is I ended up with a non modular psu. So thats a pain. However my plan was to buy a 540 air and some extensions so i can stick that psu in the back and only have the leads I need coming through. Then have 3 120mm fans in front and one in the rear. Now my CPU cooler Is doing a decent enough job I think its at 4.6 and sits around 60 but would an AIO water solution help to keep my GPUs cooler because theres less hot air being dumped into the case.
Whats the best course of action here that isnt a full waterloop as thats going to go far over budget. Ideally id like to be in the £300-£350 region to fix this.
It also needs a dust. Thats my job on saturday.