I still like Noctua fans in general, one higher pressure one might be nice there, over stock.
I'm sure would be quieter for what it is.
Yeah, I'll stick a old one in here
I still do not trust AIO's myself.
Is the upper drive bay empty? If so, that's a great spot for a 140mm Noc intake fan. Or are you running the system with the side off?
Fun stuff to mod:
10 minutes with a nibbler/aviation snippers to open up that exhaust fan area. Replace with an old skool wire fan grille. Or...rely on your old friend Bernoulli, remove the exhaust fan and let the fans on the cooler push out the hot air. They are so much stronger than that stock exhaust fan anyhow.
And...if you want to get all scientific and stuff (and who does?), could invest less than
$10 in a digital thermometer with a remote probe. Put the thermometer outside the case and place the remote probe just in front of the cooler intake fan. Secure using twist ties/duct tape/willpower/luck. Test at idle and load. Note the temp gradient. If it's more than 4-5c hotter inside the case than the outside ambient, then there's some airflow gains to be made. If you want to. ;-)
Oh and remove all those exhaust blocking pci slot covers...sure they serve a wonderful cosmetic purpose because they make a sleek finished system appearance when you have dinner guests over to stare at the back of your case. Despite that, those cosmetic demons are forcing hot air from the GPU to recirculate in the case to be ingested by the cpu cooler or GPU cooler. Is that a blower style cooler on the GPU? Not as big a deal then. If it's an 'open' style, then it's a big hot mess. ;-)
I'm not saying you need to get dremel happy and cut a 120 to 140mm hole in the bottom of the case and install another 120-140mm intake fan. No, I'm not saying that. If you get the idea to do that, it wasn't me, it was just something you read on the internet. ;-)