64bit bus should be "enough" if that's gddr5 - for comparison Barts has 7 times the SIMDs, 8 times the ROPs but only 4 times the bandwidth.6400M - 160 SPs/8 TMUs/16:4 ROPs - Interesting but Jesus it's on a 64 bit bus.........(but available with DDR3 or GDDR5).
In theory it shouldn't really require a whole lot more bandwidth than Cedar, since it's got the same amount of tmus and rops, "only" alus (which don't really require memory bandwidth) have increased.
I agree Cedar felt a bit anemic - even more so since it was a tiny bit slower than HD4550 (at the same clocks, due to the interpolation being handled in alus, so it really could have needed more alus).It's a performance gap AMD should've filled a while back in the 3xxx series, or at least had a 160 SP part as the lowest end for desktop parts when the 5xxx series arrived. I'm very interested to see how it does in it's GDDR5 form.
That said, look at the transistor count of Caicos compared to Cedar - looks like it's got a faster frontend too. In any case, unlike Cedar it should be a decent step up from intel HD 3000 graphics.
Well, unlike some other company AMD doesn't make 100W TDP mobile chips, hence there's not really that much space for different 256bit chips...And yay for the return of 256 bit memory buses to AMD's high end mobile graphics, but only on the 6900M