In an attempt to reduce the VRM throttling, I removed the C7's 92x15mm fan and replaced it with an NF-A12x15 120mmx15 fan which I mounted to the top of the DeskMini 310 case. The ventilation holes are almost the perfect size for a 120mm fan, but I used my handy mill drill to add a few more. The Noctua fan fits perfectly (just brushing the C7 fins as you slide the motherboard tray into the case). I think a little more air is blown around the CPU heatsink and onto the VRM heatsink, but the system still throttles during AVX instructions. Oh, well.
I like the Noctua fan a lot more than the original C7 fan though. The Noctua's PWM support is very impressive and my fan will throttle reliably down to 10% producing ~250 rpm (max is 1850). When the CPU is below 50C I have the fan curve set to off to prevent dust from being blown into the computer when it is idle.
Definitely a fun little box... If I had to do it again, I think I would use the standard C7 instead of the C7 Cu which makes the unit rather heavy.
--Bob