Re: Performace loss with time?
Just a thought. Have you noticed a drop in the +12V rail over periods of extended gaming? The 350W rating on your psu probably is conservative as on most quality units but it may be operating close to its upper rating. Modifying the unit's cooling arrangement might create a higher than normal heat build up and affect the psu's performance over prolonged gaming sessions.
I doubt this is the case since you are not experiencing any instability but just something to check.