Ysbl

What's the difference between a 256/448/128 bit memory bus?

__________________
You know that guy ripping apart your team with a sniper rifle? Yeah... Sorry about that.

Currently Playing:
NeoTokyo
Garry's Mod
Torchlight

Somenoob

Wider/more "lanes" for data. The bigger the bus, the bigger the amount of data (bandwidth) that can past through it. Memory Speed also plays a factor in determining bandwidth.

__________________
You are now breathing and blinking manually.

Ysbl

So 128 would be half as fast as 256 nbit, memory wise??

__________________
You know that guy ripping apart your team with a sniper rifle? Yeah... Sorry about that.

Currently Playing:
NeoTokyo
Garry's Mod
Torchlight

Somenoob

If the effective speed of the memory is the same than yes the bandwidth would be cut in half. But don't let the memory width dictate your purchase of a video card. Go by its performance.

__________________
You are now breathing and blinking manually.

logan

Yep, bandwidth is what you're indirectly talking about.

The bit width is exactly what it was described as, how wide the lane is, while the memory speed was only slightly mentioned.

Think of it like this, bit width*memory speed = bandwidth. So a larger bandwidth can help a card be faster (but SO many other things come into play here, that this is an oversimplification). Basically all the bandwidth tells you, is how much information that the card can chew through at a time.

So its like this:
a 128 bit card with 1200MHz memory should theoretically have the same bandwidth as a 256 bit card with 600MHz memory.

This is part of why a 4850 is slower than a 4870, because both use the same chip and bit width, but the 4870 uses memory that is twice as fast.

Hopefully that helps you out some

Cheers!

__________________