Maximum CPU generated frame rates when limited by Bus Bandwidth
  PCI PCI-X AGP PCI-Express
  ("normal" PCI is 32/33 PCI)      
  32/33 PCI 64/33 PCI 32/66 PCI 64/66 PCI 32/100 PCI-X 64/100 PCI-X 32/133 PCI-X 64/133 PCI-X 64/266 PCI-X 64/533 PCI-X 1xAGP 2xAGP 4xAGP 8xAGP x1 PCI-E x4 PCI-E x8 PCI-E x16 PCI-E x32 PCI-E
  bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth = bandwidth =
X Y 133 MB/s 267 MB/s 267 MB/s 533 MB/s 400 MB/s 800 MB/s 533 MB/s 1067 MB/s 2,133 MB/s 4,267 MB/s 267 MB/s 533 MB/s 1,067 MB/s 2,133 MB/s 250 MB/s 1,000 MB/s 2,000 MB/s 4,000 MB/s 8,000 MB/s
(pixels) (pixels) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s) (frames/s)
1600 1200 17.36 34.72 34.72 69.44 52.08 104.17 69.44 138.89 277.78 555.56 34.72 69.44 138.89 277.78 32.55 130.21 260.42 520.83 1041.67
1920 1200 14.47 28.94 28.94 57.87 43.40 86.81 57.87 115.74 231.48 462.96 28.94 57.87 115.74 231.48 27.13 108.51 217.01 434.03 868.06
1920 2400 7.23 14.47 14.47 28.94 21.70 43.40 28.94 57.87 115.74 231.48 14.47 28.94 57.87 115.74 13.56 54.25 108.51 217.01 434.03
2048 1536 10.60 21.19 21.19 42.39 31.79 63.58 42.39 84.77 169.54 339.08 21.19 42.39 84.77 169.54 19.87 79.47 158.95 317.89 635.78
2560 1600 8.14 16.28 16.28 32.55 24.41 48.83 32.55 65.10 130.21 260.42 16.28 32.55 65.10 130.21 15.26 61.04 122.07 244.14 488.28
3840 2400 3.62 7.23 7.23 14.47 10.85 21.70 14.47 28.94 57.87 115.74 7.23 14.47 28.94 57.87 6.78 27.13 54.25 108.51 217.01
NOTES:
1 PCI and PCI-X are described here as: (bus width in bits)/(clock rate in MHz).  So "32/33 PCI" is a 32 bit bus operating at 33MHz (this is what almost everyone has in their machine, and is what is almost always meant when someone says "PCI").
2 PCI-Express can both transmit and receive data at the same time.  The numbers provided for bandwidth in the table above are the bandwidth available per direction.  Thus x1 PCI-E has a total bus bandwidth of 500MB/s, 250MB/s in each direction.  The CPU
generated frame rate is limited by the amount of data that can be moved from the CPU to the video card.  Thus the number shown is the amount of bandwidth available in one direction.
3 These are theoretical upper limits.  No effort is made to show the effects of other system tasks.  Other system tasks (e.g. reading data from the hard disk) are much more likely to affect PCI devices than devices that use PCI-X, AGP, or PCI-Express.
4 While specified, 266MHz and 533MHz PCI-X are not available in the consumer marketplace, nor even mid-range servers.
5 At 133MHz and higher PCI-X is permitted to have at most 1 slot per bus.