sabeehali said:
From what I have read the only difference between GDDR3 and DDRII is memory speed, I mean aside from different clocking etc. The main performance advantage is that GDDR3 will be introduced at around 800 MHZ long b4 ddrII but with QDR they can achieve it even quicker ( I mean effective bandwidth) Since 400 MHz QDR should not be a problem and since Via has started supporting QDR too ...... Do you really think routing and internal design is going to be a BIG problem ?
I think the main attraction of QDR was that it wasn't too hard to implement and with much better results than traditional DDR.
The QDR implementation that VIA is working on (Kentron's QBM), requires support chips (FET switches and clock generation circuits) on each DIMM in addition to the actual DRAM chips - the DRAMs themselves are still just plain old DDR chips. Doing such a solution on a graphcis card will result in a rather large and crowded card, especially with a 256-bit bus. Also, I haven't heard of any QBM implementations working at more than about 166 MHz x 4, which is in about the same speed range as the DDR-I chips on graphics cards now. Other QDR schemes may avoid the support chips, but they need to produce a high-speed (4x or so) clock internally in order to be able to do the QDR signalling out where SDR/DDR chips can just use the standard clock signal.
The way I see it, QDR in general gives the same kind of speed boost as DDR-II, but is more complex to implement.
