Originally Posted by Buzz247
Hold on guys - keep this simple - Think about it....
Assuming there is no overclocking going on and we are only dealing with stock values:
r9 280 FX 250W TDP EACH
result is 585W TDP to be dissipated.
You dual rads can efficiently dissipate about 200-230w each. Even if we assume a perfect environment, loops and situation (which is near impossible unless in an environment controlled lab) and they are able to efficiently perform at 230w each, that still leaves 135w shortage.
Bottom line... you have WAY too much on that loop for that small of rad surface. To efficiently cool and maintain a decent equilibrium during heavy gaming, mining, etc, you would need 2x360 at least and prob an additional 240 or 120.
I might add in here: your pump res combo is severely lacking in power for the size loop and restriction you have. that 750 (x20 pump) is notoriously underpowered. You really should have gone with the D5 version of that res combo. The lack of flow + lack of rad space + poor fans = high temps. Fix these and you will see changes.
Some valid points, however even a 240 Rad with GOOD fans would cool better than the temps he's getting.
OP, do this:
Remount your CPU block. Pull it off, clean the Thermal Paste off, re-apply and then mount the CPU block again. 70C is awful, so I believe this is a mounting problem.
Also, get some better fans. Those XSPC fans would be better than the Cooler MAsters, but you really need to get some better fans. Those Yate Loons another user linked would be good fans (you don't need to spend 20 bucks per fan to get good performing fans).
Additionally, as Buzz247 stated, you should look in to getting another, thicker 240 Rad and a better pump. I would also advise you read up on watercooling a bit more so you understand what you need to consider when planning your next loop. It's a lesson learned, we all do this kind of thing so don't take our advice as coming down on you, we're just trying to help you get your system to run efficiently so you can be happy.