This will not affect the performance of you processor. Our newer cards are a bit shorter. Due to their light weight it is not necessary for them to reach the bracket in some taller cases. This is not a problem. The PowerForce card will work in a Powerbase Computer.
Boards currently being manufactured are user configurable for powerbase compatibility.
Switch 8 on the new Powerforce G3 will enable powerbase compatibility if in the down position. Some PowerTower Pro systems may not work if switch 8 is in the down position. Make sure you have updated your G3 Software to the newest versions. MacOS X Server is compatible with our cards in the current release, but may have trouble enabling the cache on earlier zif cards and non-zif cards. We are working on a fix for this and expect to have it out before the next version of OS X ships.