The idea of switching the fans couldn't leave me!!! arrgh!
So I just went and did the short experiment.
The results? I found that changing the top fan from inhale to exhale made it worse for at least the CPU. Had the computer running at full load for all tests, for 30 mins (which IMO is long enough to generate all the heat needed).
This is how I did it:
I just ran the comp with CPU fan at min, ran 1xtoast.exe (nice little prog to use all CPU power) and ran 3DMark 2005 with that (to use up graphics). Takes a couple of runs to meet the 30 min requirement. Had Everest running in the background on sensor page to get the reading as soon as 30 mins is up.
Without doing anything, I turned the CPU fan to max, did everything again for 30 mins, and recorded the temp.
Switched the fan so its now on exhale. (Found that I had to rethread the fan to do that)
Repeat.
Results:
Fan on inhale:
CPU fan running on min: 31C
CPU fan running on max: 26C
Case temp from case sensor: 24.5C
GPU: unreadable, kept jumping from 33-64C. Unreliable so I'll just dump this data.
Fan on exhale:
CPU fan running on min: 31-32C
CPU fan running on max: 26C
Case temp from case sensor: 24.7C
Conclusion: Not much of a difference, but it is clear that for me at least, having the case fan at exhale doesn't seem to lower the temp, but increases it very little. Of course, this test has to be repeated a few times before we can make some solid conclusions.
As I see it, my comp even at max load doesn't really produce much heat, especially in winter. I might just wait for summer to come up to re-do the test, but someone else is welcome to try it and share the results.