RDRAM-How do they arrive at PC800?

[Treeburst155]

I understand how they come up with DDR specs like PC1600 and PC2100, but how do they do it for RDRAM? Current RDRAM runs on 100 mhz FSB. How do they come up with the 800? Just curious, and thanks for your time?

Treeburst155 out.

 

[Jaimin]

RDRAM that is PC800 runs at 400mhz and is ddr which effectively doubles the throughput. This is where they get PC800.

 

[Treeburst155]

I get it now. Thanks! Now I understand what people mean when they speak of RDRAM being "quad-pumped". 100 mhz FSB x 4(quad pumped) x 2(DDR)=800. There must be a multiplier on the motherboards, eh? Thanks again. I really appreciate it.

 

[imgod2u]

no, the P4's FSB is "quad-pumped" 100MHz, NOT RDRAM. RDRAM is 400MHz 16-bit channel running DDR, P4's FSB is 100MHz 64-bit Quad-pumped. Do a little math:

16-bit x 400MHz x 2 (DDR) x 2 (dual channel) = 25600 megabits per second = 3200 MB/sec = 3.2 GB/sec

64-bit x 100MHz x 4 (Quad-pumped) = 25600 megabits per second = the exact same thing as above.

 

[thermite88]

For the DDR SDRAM:

64-bit x 133MHz (Bus) x 2 (DDR) = 17024 megabits per second = 2128MB/sec

They use the theoretical bandwidth for naming convention, thus, PC2100.

RDRAM is 400MHz 16-bit channel running DDR. They use 400MHz x 2 and call it PC800. The actual bandwidth is 3200 MB/sec. If they use the same naming scheme as the DDR SDRAM, it would be PC3200.

 

[Degenerate]

god io wish DDRSDRAM and RDRAM will just come together into one super memory... its hard but i want it.

 

[Kingofcomputer]

they cannot come together, they're different architecture/technology.
we don't need them come together, only sdram type is enough.