I see this has turned into a 'heated' discussion
Well, i've bodg..., damn, carefully crafted a CPU duct out of thick printer paper and sellotape and it seems to be OK so far! The fan on the CPU is actually 70mm so I put the duct over the fan so it's enclosed and can only draw air from the within the duct that's being blown in from outside. Also stuck a bit of filter material over the inlet so it doesn't suck dust in! I also had to remove one of the fans from the side as it was in the way of the duct!
Ran 3DMark06 with the case lid off and then case lid on and the CPU Fan never went above 4,000 RPM, it did hit 5,600 previously, and CPU went between 55°C - 60°C
Was running ANUS Probe II so not sure how accurate the fan speeds/temps are being reported.
Currently it's idling at 3,600, CPU temp 43°C and I never thought to record the temps without the duct in place
So it 'appears' to work for keeping the CPU cooler than without a duct, but as people will point out, not as good as a breeze block sized heatsink with a fan nailed to it bolted onto your CPU and mobo
Anyway, I've achieved what I wanted, made a CPU duct and luckily it's working to keep the CPU cool enough to stop the Fan going into turbo mode! How long it will stay like this is dependant on the room temperature and not pulling in warmer air that will increase the CPU temp. Think I'll load Oblivion and see what happens!
I'll have to raid the piggy bank to afford that Noctua though, sell a kidney, maybe an arm or leg and possibly a lung or even rob the shoolkids of their dinner money
