ATI Multiple VPU works with two different cards
 

ONE OF THE HUGE advantages of ATI Multi VPU might be its ability to let you use two different ATI based cards. As we said before, ATI Multi VPU don't use any card interconnector although Nvidia does.
In Nvidia's case you cannot even use two 6600GT or 6800 GT cards from two companies since there may be incompatibilities. It is a problem even if you use different BIOSes on the cards. Two different cards simply won't work in this case.

ATI will let you use two different cards as its Multi VPU works in a different way. It tiles your screen like a chess board and each board can take care of different "chess fields". You will literally be able to take an R520 and plug it side by side with R423, X800 or R480, X850 board and make them render simultaneously. Faster boards could, for example, take on more tasks than slower board, rending more fields.

Sounds good to me, but let's just see the drivers and performance of that Multi VPU marchitecture first. We heard a while ago that ATI has this marchitecture ready but it wants to wait with it and than surprise everyone. It will possibly materialise this marchitecture after the R520 "Fudo" launch. µ
http://www.theinquirer.net/?article=22485