@64 Dragon - Have you tuned your CPU and NB GTLs? What are your temperatures like, and do any of them get higher in WCG than when testing? I only mention this because I've recently discovered that my PWMs get too hot and have the same kind of effect.

On another note, I've been running a little experiment to determine the effectiveness of the Asus cooling solution to my own consisting a NB waterblock on the P45's die (Shared with CPU), 2x copper enzotech mosfet sinks and a aluminium chipset HS for the SB. Here's what I recorded:

______|1___|2___|3___|4___
CPU__|72°C |71°C|82°C |78°C
NB___|47°C |51°C|47°C |51°C
SB___|40°C |48°C|40°C |49°C
MB___|34°C |34°C|34°C |34°C
PWM_|60°C |57°C|64°C |61°C

1: Custom cooling - 1024K FFT test (31°C ambiemt)
2: Asus cooling - 1024K FFT test (28°C ambiemt)
3: Custom Cooling 8K FFT test (31°C ambiemt)
4: Asus Cooling - 8K FFT test (28°C Ambiemt)

I set the motherboard to all auto, with CPU level up to 'Crazy' giving 389*9 with memory at 933. Voltages were left to generate the heat, and were as follows:
Vcore: 1.488
Mch: 1.32
VTT: 1.31
PLL: 1.79
SB/1.1: 1.5/1.12
DDR: 1.86

As you can immediately see, the SB benefits greatly from being cooled on its own by plummetting by nearly 10°C, and that's with 3°C Higher ambient temps! It's clear from this alone that a lot of heat spreads towards this part of the Asus cooler
The northbridge shows expected results with a drop of 4°C (probably more if the ambiemt temps were the same) when it is cooled on its own.
The PWM seems to suffer the most when cooled on its own as it runs 3°C higher, and although this could be down to the ambiemt temps, judging by the part of the case it is in (i.e. v.little airflow in that area) I would say that it needs the extra cooling when running with higher voltages.

So it looks like I either need some mosfet blocks, a better PSU (a small chance), or will have to get another fan going on the mosfet area (which I really want to avoid, as I'm aiming for a semi-passive setup). Does anyone experience worse PWM temps with a naff PSU compared to a good one, or can anyone test this for me? This will probably make my decision to go for a Corsair HX850 at the end of this week, so accurate feedback would be very useful in making a decision about this issue.