Proper GPU bandwidth interpretation

[stmpdyrd]

Hi All,

I was researching on how GT 240 GDDR3 differed with its GDDR5 counterpart and if having PCI 1.0 -> 3.0 would matter as a bottleneck.

Here are the bandwidth i got from wikipedia:

PCI Express 1.0 (x32 link) = 64 Gbit/s 8 GB/s
PCI Express 2.0 (x16 link) = 64 Gbit/s 8 GB/s
PCI Express 3.0 (x16 link) = 102.4 Gbit/s 12.8 GB/s
PCI Express 2.0 (x32 link) = 128 Gbit/s 16 GB/s

What I want to understand is how the computation really works, since the rated Bandwidth, say for the GT 240 GDDR5, is at 54.4 GB/s, which is so much higher than those specified by the bus bandwidth capcities.

http://en.wikipedia.org/wiki/GeForce_200_Series

Help how to interpret these numbers?

 

[eyefinity]

The card bandwidth is the memory bandwidth, it's got nothing to do with the pci-e slot.