RAM MHz

Apathetic

New Member
When I see ram theres always a MHz after it. What does the MHz do besides making it better :P Also, would you notice the difference between 1024MB 333MHz and 1024MB 400MHz?
 
MHz is the unit of measurement meaning millions of Hertz or millions of cycles per second. Between 333MHz memory (which is actually clocked at 166MHz) and 400MHz (which is actually clocked at 200Mhz) you probably wouldnt notice much difference.
 
How do things like PC800, PC3200, and PC2 3200 all relate?

My computer has 512 of rambus, which I assume is PC800. But what I don't understand is the relation between GB/s and MHz.

PC800 is 3.2 GB/s on some models and many models of PC3200 are 3.2 GB/s. How can I compare RAM and know which is better?
 
For DDR SDRAM in the PCxxxx designation the xxxx is the memory bandwidth in MB/s i.e. PC3200 is 3200MB/s. This corresponds to a 200MHz clock (400MHz "data rate"). Since DDR SDRAM uses a 64-bit wide bus (8 bytes wide), 8 bytes * 400 MHz = 3200MB/s.

RDRAM (PC800) use a 16 bit wide bus running at 400MHz. With DDR signaling this equals 800MHz transfers. This is an on-stick bus, the system BUS is 400MHz and 64 bits wide. RDRAM is installed in pairs (dual channel) each giving a peak bandwidth of 1.6 GB/s which equates to 3.2GB/s
 
Cromewell said:
This corresponds to a 200MHz clock (400MHz "data rate").

What is a 200 MHz "clock" versus a 400 MHz "data rate"?

Cromwell said:
RDRAM is installed in pairs (dual channel) each giving a peak bandwidth of 1.6 GB/s which equates to 3.2GB/s

So does this mean that 512 MB PC800 is "faster" or more efficient than 512 MB PC3200? I'm assuming since it's dual channel that the pair can run together faster than the 3.2 GB/s, but I'm not sure if that's correct.
 
It's 200MHz clock but because they are DDR they can transfer on the high and low of the signal band making it effectively 400MHz.
So does this mean that 512 MB PC800 is "faster" or more efficient than 512 MB PC3200? I'm assuming since it's dual channel that the pair can run together faster than the 3.2 GB/s, but I'm not sure if that's correct.
No, the fastest a single stick of PC800 can run is 1.6GB/s, only through dual channel can it reach 3.2GB/s
 
So I guess that's why DDR3200 seems to be the most popular across the board with people who build computers?

What about DDR2? I haven't seen too many people looking for that.
 
DDR2 is getting better, it's not too popular yet because of the high price and latencies (and AMD doesn't support it yet).
 
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