PDA

View Full Version : Need Help with memory ratings :(

Darkpie
05-07-02, 01:01 PM
Ok i have been reading a lot in the forms and on the net and i still am lost about how they get the Clock speed for SDRAM and DDRAM and RDRAM. From what i understand it is somthing to do with a 4X or 8X times the FBS or something like that then you times it by 133 or somthing. I am lost real bad lol

So if you can help me pleas do. Thank you all

Jon
05-07-02, 01:35 PM
SDRAM runs at the same as the bus clock. 100MHz bus speed is PC100. 133MHz is PC133.

DDR runs at double this data rate, hence DDR. 100MHz DDR is 200MHz (PC1600 or 1.6MB/s bandwidth), 133MHz is 266MHz (PC2100, 2.1MB/s), 166MHz is 333MHz (PC2700, 2.7MB/s) and 200MHz is 400MHz (PC3000, 3.0MB/s).

RDRAM is quad pumped and works on the same principle...100MHz is 400MHz, so on so forth.

Darkpie
05-07-02, 07:50 PM
Thank you Jon for the info that helped me out a lot.

:D

Daovonnaex
05-07-02, 11:36 PM
What's less important than the clock speed of memory is the bandwidth it provides. To get a bandwidth statistic for the memory, take the clockspeed in MHz and multiply it by the bit-width (i.e., 64-bits for DDR SDRAM, 32-bits for dual-channel RDRAM), then divide by eight to get the bandwidth in megabytes per second. For example, DDR266 then has about 2.1GB/sec of bandwidth (hence PC2100 DDR SDRAM). PC800 RDRAM has a 3.2GB/sec of bandwidth. SDRAM is rated by its clockspeed, DDR SDRAM by its bandwidth, and RDRAM is also rated by its clockspeed.

Darkpie
05-08-02, 08:37 PM
Ok one quick question Can you figure out the Band with of
PC133 SDRAM by going 133x64=8512 Then Divide 8512/8 wich gives you a PC133 Bandwith of 1.0GB/Second