Eracer:
Another look at your post also shows that you ascribe to me things that I did not say. The thing was that a 64 bit memory controller, 64 bit ring bus, setup engine, 4 ROPs, UVD, 16x PCIe interface and Tesselator uses 40mm2 of the 55nm RV610 die. Then some intellabee took that to mean just for the memory controller and forgot the rest and assumed that there were 4 equal copies of it in the R670. Well given the above there would be 256 bit memory and ring bus, 4x the setup engine and 16 ROPs, but there isn't 4 Tesselators, 4 UVDs, 64x PCIe so that number is high.
Although given that a R770 is 260mm2, some 68mm2 bigger than the R670's 192mm2 on the exact same process where there is 2.5x the stream processors and much else is roughly the same, that the 68mm2 is equal to 1.5 times the original 320 stream processors and 16 TUs. Thus one set of them is 46mm2, making all of the rest (non stream processors or TUs) use the other 146mm2. My original back of the napkin estimate isn't far wrong. The big thing that would have been missed is the use of a crossbar switch and hub instead of the ring bus probably saved more die area some of which was used to beef up the ROPs, make the PCIe version 2.0, revise the UVD to UVD2, allow for remote memory accesses through crossfire or PCIe interface and upgrade the memory controllers to handle GDDR5.
The same is true of the Atom. Although its stated all over that it uses 2.5W, that does not include the NB or memory controllers which add another 5.5W for a total of 8W. There are 1GHz 90nm Semprons that use 7.7W including a dual channel DDR2 memory controller and they being fully three issue out of order processors, have far more IPC than Atom does. They likely run rings around the Atom. There is even a 6W Geode NX1500 which is really a 1GHz 130nm bulk Athlon K7 which likely still runs rings around a 1.8GHz Atom also because its three issue OOO processor. You have to add in the NB, but given that it uses very cheap 130nm bulk likely sells for less than Atom.
Besides without adding in the other power users in a netbook, comparing processors performance per watt leads to garbage results as users look at the netbook as a whole, not at just the CPU core. A 2.5W Atom that gets 1x in performance might look good on paper versus a 7.7W Sempron that gets 2x. But in a netbook where the screen uses 10W and the DDR2 memory uses another 5W, the Atom powered netbook uses 23W (you have to add in the chipset) and the Sempron netbook uses 26W (the chipset doesn't have the memory controller just a small IGP like a M740G/M700SB which still would vastly outperform the IGP in the Atom chipset). Then the Sempron has a 13W per unit performance while the Atom has 23W per unit performance. And if the Sempron was upclocked to 2GHz and uses 25W, the netbook goes to 51W but has 3.5 times the performance for an increase to 14.5W per unit performance. Still higher perf/W than Atom's when looking at the netbook as a whole.
Pete |
