Out of my ~400 units for the last month, only two of them were invalid. If my CPU is able to crunch through more work units more quickly and efficiently, there will be more benefit towards the study.

My CPU is overclocked and stable for other purposes other than crunching.

Blizzie,

I agree with the above. All of my machines have some degree of overclocking applied to them and I have never had any issues. If you know what you are doing and are using quality components, I do not see any issues. Got to be honest though, I never overclock by more than 15% (10% on some machines), purely do to the fact that my processors run at 100% 24/7/365.

my brief attempt at OC showed that some projects are more sensitive than others. If I remember correctly, FAAH went ballistic on one of my OC machines, while the other projects just finished faster. ACH had one invalid on another OC machine, but that WU had 8 invalid, 1 error, and 13 valid hits, so I question whether that was just a WU glitch.
I also found it interesting that the floating point unit showed a significantly higher boost than the integer unit for the specified OC. I would have expected a more linear boost, but that's a discussion for another thread.

You should probably post this in the WCG team section of XtrememSystems.org/forum. You'll need to register first of course - but that's just for the forum not for the WCG team.

I have 2 Q6600's "designed" to run at 2.4 ghz. I'm running one at 3.6ghz and it has only produced errors when I had changed something and it was not yet stable. The other is at 3.2ghz and I won't bump that up again until the thermal paste has settled.

There's no issue with running apps at ANY speed that the chip will tolerate. The only difference for example between chips with the same architecture, stepping, etc that run at different rated speeds is that the faster chips can get away with it and the slower ones can't. There's no design limitation on speed until you get into truly extreme overclocking. Using liquid nitrogen I believe, the Q6600 has been run at 5ghz. Will every q6600 be able to do that? No. But some can.

The best way to check stability and temperatures is to run something like Prime95 (select options --> torture test --> 'in-place large ffts') - dl from http://www.mersenne.org/freesoft.htm (thanks to XS_Olympic). If you can run this for a couple hours and not get any errors or thermal checks, you will probably be ok.

But remember, if you are pushing the envelope, your system will be much more sensitive to external factors like ambient temperature, dust build up in heat sinks, etc. If you don't keep an eye on your system daily and check it's health status with something like speedfan or a similar utility, you could fry your system.

There is a software package called the oc bible that has a lot of free utilities for overclockers.

speedfan - http://www.almico.com/sfdownload.php
oc bible - http://www.softpedia.com/get/System/System-Miscellaneous/OcBible.shtml