Quick, hopefully easy question about RAM speeds

[Jeff7]

I'm a bit confused about RAM speeds nowadays. I last checked in on the hardware scene when PC-3200 was all the rage. Now I'm using PC2-6400.

What speed does it run at? No one ever kept it straight in the PC-3200 days. People said it ran at 400MHz. It was actually 200MHz, but with two data transfers per clock cycle. Is that still the case?
I've got some PC2-6400 RAM, and the websites like Newegg, or the manufacturer's websites, say that it runs at "800MHz". CPU-Z says that it's running at 400MHz.

So confirm if this is correct:
- My RAM is running at 400MHz.
- Its effective speed is 800MHz because it is doing two data transfers per clock cycle
- Manufacturers just say "800MHz" because your average computer user doesn't understand DDR technology.

 

[themisfit610]

If it says DDR2 800, then it's good to run at a 400MHz clock - which is 800MHz DDR.

Honestly, the difference in RAM speed alone in a system makes so little difference it's not even funny 🙂

It's all about having RAM thats fast enough to go 1:1 toe to toe with an overclocked Core 2 Duo 🙂 You can hit 500MHz (1GHz DDR) with sexy fast RAM on a good Core 2 board like a 680i or 975x.

 

[Aluvus]

DDR uses a two-bit prefetch; every complete clock cycle it outputs 2 bits of data. DDR2 uses a 4-bit prefetch. More at Lost Circuits.

 

[sonoma1993]

Originally posted by: Jeff7
I'm a bit confused about RAM speeds nowadays. I last checked in on the hardware scene when PC-3200 was all the rage. Now I'm using PC2-6400.

What speed does it run at? No one ever kept it straight in the PC-3200 days. People said it ran at 400MHz. It was actually 200MHz, but with two data transfers per clock cycle. Is that still the case?
I've got some PC2-6400 RAM, and the websites like Newegg, or the manufacturer's websites, say that it runs at "800MHz". CPU-Z says that it's running at 400MHz.

So confirm if this is correct:
- My RAM is running at 400MHz.
- Its effective speed is 800MHz because it is doing two data transfers per clock cycle
- Manufacturers just say "800MHz" because your average computer user doesn't understand DDR technology.

yeah im in the same boat as you. I'm confuse as hell about ddr II mhz ratings

I have these memory sticks in my system
CORSAIR XMS2 DOMINATOR 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Retail

my motherboard detects it as ddr2 800. So does my memory run at 200mhz or does it run at 400mhz? Right now I have my amd athlon 64 x2 4200 overclock to 2.6ghz
(fsb @ 236mhz). So do I more room to overclock with my memory I'm using?

 

[John]

Originally posted by: sonoma1993
my motherboard detects it as ddr2 800. So does my memory run at 200mhz or does it run at 400mhz? Right now I have my amd athlon 64 x2 4200 overclock to 2.6ghz
(fsb @ 236mhz). So do I more room to overclock with my memory I'm using?

If your memory divider is 1:1 then your memory is running @ 236MHz

 

[sonoma1993]

Originally posted by: John

Originally posted by: sonoma1993
my motherboard detects it as ddr2 800. So does my memory run at 200mhz or does it run at 400mhz? Right now I have my amd athlon 64 x2 4200 overclock to 2.6ghz
(fsb @ 236mhz). So do I more room to overclock with my memory I'm using?

If your memory divider is 1:1 then your memory is running @ 236MHz

i checked my memory with cpu-z. It say it currently running at 236.0mhz Looks like it running a memory divider 1:1.

now with cpu-z, on the memory tab, under timings. It says FSB : DRAM CPU/5. What does that mean?

that 236.0 mhz is with minimal power mangement enable in power management in the control panel. When I set it to home/office, my memory jumped up to 432.7mhz. And that FSB : Dram went to CPU/6