Asus 4870 Question

[Rmgdx]

Asus 4870

What does "Memory Clock-3600MHz (900MHz DDR5)" mean?

It's the only one like that I believe, the rest say 1800MHz.

 

[Apokalipse]

the GDDR5 used on the 4870's is clocked at 900MHZ, but has an "effective" speed of 3600MHZ
what that means is, even though it isn't actually clocked that high, it can transfer data as fast as GDDR1 would be able to if it were clocked at 3600MHZ

GDDR3 has double the bandwith at a given frequency than GDDR1, and GDDR5 has double the bandwith at a given frequency as GDDR3
that's why 4870's have memory bandwith so high, even with a 256-bit memory bus.