Calculating theoretical mem bandwidth

[fbrdphreak]

Hey guys,
Just want to make sure I'm doing this right. Need to calc some theoretical mem bandwidth of DDR2 533:

bandwidth = (2 transfers/tick)*(266*10^6 ticks/sec {MHz})*(8 bytes / transfer) = 4256*10^6 bytes/sec = 4256 MBytes/sec

Is that right?

Also, is it correct that the high latency of DDR2 533 prevents it from reaching this theoretical bandwidth?

TIA

 

[ViRGE]

Close, the base clockspeed is actually 133mhz, and the transfer/tick rate would be 4 in this equation due to the fact that the prefetch is 4bits instead of 2bits(so it's actually still 2 transfers, but we will call it 4, get that?). See this AT article for a better understanding if you're still confused. And yes, the latency is a big part of the reason why it can't reach the theoretical numbers.

 

[fbrdphreak]

Doh, I forgot that Intel quad-pumps their bus. Still comes out the same tho right, I just had double the clock and half the transfers.