The G450 is a die shrink for the G400 core using .18-micron process technology, and Matrox has used the extra chip real estate to integrate a number of components, including a second RAMDAC (for DualHead), a TV output, and a TMDS transmitter for digital flat panel displays.
Obviously, bringing these components on-chip will help cut production costs on G400 cards, as should the move to DDR memory in the long run. So the G450 should be cheaper than the current G400 cards. But what about performance?
Well, first off, Matrox isn't gunning for the high end of the enthusiast market with the G450; we'll have to wait until their Next Big Thing hits to see something competitive with the GeForce/Voodoo 5/ATI Radeon triumvirate. The G450 is aimed at corporate users, and Matrox would love to see the G450 earn them some OEM deals in this market.
Unlike the G400, the G450 uses DDR memory, which should double memory throughput, all other things being equal. Howeverand I don't believe you will find this info in the press releasethe G450 has only a 64-bit memory bus, while the G400 has a 128-bit bus. (Matrox calls the G400's 128-bit bus a 256-bit DualBus; for more info, see here.) In short, the G450's theoretical memory throughput is the same as the G400's.
However, for what it's worth, the G450 should be able to run at higher clock speeds than the G400 if the .18u die shrink works as one would expect. Matrox isn't making any big claims on this front, and the company was still doing board-level tests to determine final clock speeds for the G450 cards when we spoke, but I expect we'll see a nice gain in core clock speeds on production G450s. Given the G400 MAX's monster fill rates, I wouldn't be terribly surprised to see a G450 easily outperforming any flavor of the TNT2 or maybe even a Voodoo4 card in certain scenarios. For the real 3D graphics freaks, however, the G450 isn't the ticket.