Video card buses?

[binsky3333]

I was just wondering about Video card buses. Is the bigger the bus the better. For example is a 320bit bus better than a 256bit bus?

[largon]

Not necessarily.
Bandwidth is what matters in the end.

bandwidth = bus width × memory frequency data rate

For example:
320bit × DDR-1600 = 62.5GB/s
256bit × DDR-2000 = 62.5GB/s
In this case 320bit and 256bit are equal.

[candle_86]

someone besides me understands

[wolf]

i understand too :P i find myself constantly explaining the computations for pixel and texture fillrate, memory bandwidth, and peak shader arithmetic.

knowing the math behind the cards really helps when your choosing what to buy.

[candle_86]

agreed, last time i explained that stuff i was called a liar.

[wolf]

as long as you know your are right and whoever calls you a lair is wrong then it doesn't matter, let them be ignorant if they so desire.

we can only try to help people when asked, if at that point they think were lying then screw em.

[DanTheBanjoman]

Not necessarily.
Bandwidth is what matters in the end.

bandwidth = bus width × memory frequency data rate

For example:
320bit × DDR-1600 = 62.5GB/s
256bit × DDR-2000 = 62.5GB/s
In this case 320bit and 256bit are equal.

Yet the 256Bit bus will have a lower latency. So probably has a slightly higher effective bandwidth. Your example is theoretical.

[W1zzard]

see thread here:

http://forums.techpowerup.com/showthread.php?t=53626