Very nice. Your CPU is running nice and cool because the giant fan is helping to supply it with fresh external air, hot air is then exhausted out the rear of your case rather then being re-circulated back into the cooler, nice and efficient layout!
But I think your GPU may be acting in the opposite manner. There are 2 main reasons that your GPU may be throttling:
- The Asus GPU cooler exhausts in all 4 directions (Top, Bottom, Front and Rear), I suspect this hot air will be working its way back round to the cooling fan. When the hot air exhausts from the card it will hit the side panels of your case and spray outwards in all directions - imagine spraying a hose pipe at a wall, the water sprays out in all directions. Airflow acts in a similar manner to waterflow.
- The side panel of your case is almost completely blocking the intake fan of the GPU - this is your main reason.
I think fans in general need something like 30mm of unobstructed clearance to work efficiently, obviously this isn't possible in small cases like these, so the next best thing is to provide some direct air paths to the fan such as ventilation slots or holes, this will provide the most benefit to the card allowing it to breath in cool air.
To help prevent re-circulation of hot GPU exhaust air, you could also consider some ventilation holes/slots on the top and/or bottom of your case in line with the GPU exhaust fins.
Some other things to consider - If you cut some holes in the side of your case to allow your GPU to breath, you may find that the 180mm front fan works against the GPU fan (the GPU fan is trying to pull air in, whilst the case fan is trying to push air out, the overall effect is reduced airflow into your GPU).
I suspect that in your particular layout the 180mm front case fan will work best as an exhaust fan. Your CPU may run a few degrees warmer in this configuration, but the the 180mm fan will help pull fresh cool air through the side GPU vent helping to feed the GPU, your GPU will run cooler and much quieter. The key is getting the right balance of airflow that works for all your components and not just 1 component in particular. In other words there is no point having a setup that benefits the CPU to run at low temps if your GPU is running at throttle temps and vice versa.
I ran quite a bit of testing in the LZ7 early prototypes which is a similar layout to this fan (except for main case fan position), The testing showed that a negative pressure setup (case fan set to exhaust air) greatly reduces the GPU temps which leads to lower GPU fan speeds and lower overall noise output, this is because the negative pressure is assisting the GPU fan to pull cold air through the side vents directly into the GPU. The downside in the LZ7 is that the hot GPU exhaust air is then dragged across the motherboard and into the CPU due to the location of the case fan being on the opposite side of the case, so the overall effect was a louder system as the CPU fan was running much faster. But, in your layout the fan is at the front of the case, therefore exhaust GPU air will be pulled towards the front of the case and not over the CPU.
Give it a shot and see what happens! I would be very interested to see what the difference in your results are with a positive and negative pressure setup and whether they stack up with the testing results from the LZ7.
