# 128 bit and 256 bit memory interface graphics cards... what's the difference ?



## the magical me

hello all...

what's the difference between 128 bit and 256 bit memory interface in graphics cards ???









will the 256 do better in games and video playing than the 128 ??

what would 256 add over what the 128 does ???

is there a game that really need the graphics cards to be 256 bit ???

best regards.


----------



## eseb1

the bit rate determines how fast the memory and the GPU can talk to each other basically, a higher bit interface, the faster they can talk.


----------



## GfhTattoo

Quote:


Originally Posted by *eseb1* 
the bit rate determines how fast the memory and the GPU can talk to each other basically, a higher bit interface, the faster they can talk.

Said it all. Higher the bit rate more lanes the info can travel


----------



## youra6

Off topic here, but a good FAQ for those of you who dont know what bit actually is, bit stands for:
*
binary digit (0,1)*

Ok when we are talking about bits, in different context means different things.

For example 16bit color means: 2^16 colors. Meaning the computer can display that many colors

32bit means 2^32 colors. Yeah thats a **** ton more colors but at that point your eyes shouldn't be able to tell difference (since theres soo many colors







)

This bit rating of the processor determines the largest numerical number that processor can handle.Thus, a 32-bit processor can handle a number up to 2^32. Any number greater than this will require more than one clock cycle to process.

A 64-bit processor on the other hand can handle a number of a 2^64 or This means that a 64-bit processor would be able to more efficiently handle large number mathematics.

Laughably a 4 bit computer (talking about the EARLIEST computers) can only do 2^4 bits. Therefore that means it can only calculate only 16 numbers (more specifically -8 to 7) Therefore it can not calculate any number beyond this scope.

In video cards, bits is used slightly differently. Today the memory bandwidth from128 bits to 512 bits. The maximum theoretical memory bandwidth is the product of the memory clock, the transfers per clock based on the memory type, and the memory width. For example, a video card with 200 MHz DDR video RAM which is 128 bits wide has a bandwidth of 200 MHz times 2 times 128 bits which works out to 6.4 GB/s.


----------



## sLowEnd

They are a factor in memory bandwidth.

A 128-bit bus card may or may not have less bandwidth than a 256-bit bus card.

For example, a 5750 has more bandwidth than a 4850, despite the 5750 having a 128-bit bus and the 4850 having a 256-bit one.
Why? Because the 5750 uses GDDR5. Memory type is another factor in memory bandwidth.
Looking at the bus width alone is unwise. Actual memory bandwidth is what's important.


----------



## Acoma_Andy

Quote:


Originally Posted by *the magical me* 
hello all...

what's the difference between 128 bit and 256 bit memory interface in graphics cards ???









will the 256 do better in games and video playing than the 128 ??

what would 256 add over what the 128 does ???

is there a game that really need the graphics cards to be 256 bit ???

best regards.









It highly depends on which GPU architechture it is using, and the type of memory (GDDR2, GDDR3, GDDR5). So not only the memory interface is important.


----------



## CJRhoades

Quote:


Originally Posted by *sLowEnd* 
They are a factor in memory bandwidth.

A 128-bit bus card may or may not have less bandwidth than a 256-bit bus card.

For example, a 5750 has more bandwidth than a 4850, despite the 5750 having a 128-bit bus and the 4850 having a 256-bit one.
Why? Because the 5750 uses GDDR5. Memory type is another factor in memory bandwidth.
Looking at the bus width alone is unwise. Actual memory bandwidth is what's important.

Correct. Total bandwidth depends on the bus width AND the speed of the VRAM on the card.

EDIT: Bah.. you ninja edited me.


----------



## the magical me

by the way... while I was searching google for this, I found this article from Tomshardware, so I just want to post it here , it's rather old, but still useful, so read it here

http://www.tomshardware.com/reviews/...rs,1288-8.html


----------



## the magical me

_(deleted because it was double-posted by error.)_


----------

