Bus width doesnt matter on its own.
Bandwidth is a product of memory speed and bus width. DDR5 memory is quad pumped, ie bandwitch is frequency*bus*4. DDR3 is double.
A 4850 and 4770 use different types of memory. the 4770 uses quad pumped GDDR5, the 4850 only GDDR3. The 4850 has double the bus width.. but the same effective memory transfer rate.
Daedalus685... I am curious if your video card is running DDR2 would you simply times by one?
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