ROPs / Render Backends

GT200 uses virtually the same ROP architecture as the one used on both the G80 and G92 GPUs – each ROP partition has access to a 64-bit memory channel, so given the fact that this chip has a 512-bit memory interface, there is a total of eight ROP partitions.

Each ROP partition houses four ROPs that can each output four pixels per clock with four components per pixel or 32 Z-samples per clock. In addition, GT200's ROPs can now do full-speed FP16 blends whereas previous generation ROP hardware could only manage this at half-speed. This, combined with the increased number of ROPs and wider memory bus width, should impact anti-aliasing performance in a positive manner.

And speaking of anti-aliasing, nothing has changed on that front – GT200's ROPs support all of the anti-aliasing modes supported by G80's and G92's ROP hardware. There's up to 8xMSAA and 16xCSAA, along with support for multi-sampled and super-sampled transparency adaptive AA.

What's more, all of the bandwidth utilisation and compression optimisations made in G92's ROPs are present in the new hardware, which is again good news. Image quality-wise, nothing has changed—and it's much the same as the texture sampling hardware in that respect—there's just more on tap.


Generally speaking, things went as expected in 3DMark Vantage's Colour Fill Test – the 9800 GTX's fillrate is naturally the lowest, as it can only fill at 16 pixels per clock. That's half as much as the GeForce GTX 280, 9800 GX2 and Radeon HD 3870 X2.


Oblivion is a great test in many respects, but there's one thing we realised shortly after compiling the results – it's one game where the lack of hardware-based MSAA resolve in the Radeon HD 3870 X2's render backends doesn't seem to make so much of a difference at the lower AA levels. We'll add a second test to show what happens in many other scenarios.