Differences in RAM

[Jeff Harper]

Just got the new version of my workstation running, and wow, what a difference. The only thing different is the case, MB and the PSU, and I can't believe how much better things are running.

Anyway, while I plan to OC at some point (don't have time to play with it now) here's my question.

I'm running a Q6600 and my board supports up to DDR2 1200.

My curent 8gb of ram is DDR2 667.

Regarding Vegas, would I see any difference upgrading my memory? And since I'm going to overclock for the first time, will I need faster memory to OC the processor? I know nothing about overclocking and don't know of any possilbe effect the slower old ram could affect the OC experience.

[Giroud Francois]

ram is like everything in computer.
it is designed to operate at a definite speed and voltage by design.
it is sold as working for a maximum speed, but good memory can work faster as advised.
Why going faster would you say.
The main thing you use when overclocking, is the front side bus clock.
For example a motherboard can have a frontside bus running at 667 Mhz, the processor running a a multiplied front side bus rate (x time 667).
when overclocking processor, you can either user a bigger multiplier or use a higher front side bus frequency. Most processor today have a locked multiplier, so it is not possible to use this. Additionally, modifying the multiplier makes big step change, while you can modify front side bus by 1Mhz step, so it is easier to fine tune.
Memory frequency is also driven by front side bus, so overclocking front side bus means overclocking memory too.
Memory is not alway working at same speed as the front side bus, but with a divided clock rate. (1/2 , 4/5 , 5/4, etc...).
So a motherboard running a front side bus a 1333Mhz will run 667Mhz memory with a 1:2 rate.
If you push front side bus to 1400Mhz, the increase to memory will be (1400-1333)/2=33Mhz. so your 667 memory will run at 667+33=700Mhz.
good memory can stand such increase without modification, some will require voltage increase, and some will fail.
using 800Mhz memory would solve the problem.
But if you are looking for performance, you will not use 667 or 800Mhz memory anyway.
with a 1333Mhz front side bus, you will use at least 1066Mhz memory, to get better ratio.
as 667 memory use 1/2 (means your memory is unavailable half the time), a 1066 memory use a 4/5 ratio, meaning that your memory is unavailable only one clock tick every five.
That is much better, your PC will be faster and no overcloking is required.
Ideally, you would use a 1:1 ratio meaning your RAM is working at front side bus speed.
This is possible with 667 and 1066 front side bus, but recent processor use 1333 or even 1600 speed that is not reachable even by fastest memory.
So the rule is get memory as fast as you can to get the better ratio according the front side bus. Then if it is not enough and you still need to overclock, see how much the front side bus you need. (at 1333 FSB running a 3.0Ghz, you got a 2.25 processor multiplier).
for each Mhz increase on FS, you go a 2.25 increase on processor.
So to run the processor a 3.6Ghz, you will get an increase of 600Mhz on processor, and a 600/2.25=266Mhz on FSB.
if your ram is working at 4/5 of FSB speed (=1066), the increase for ram will be 266*4/5=213Mhz. so you will need a ram working a 1066+213 =1279Mhz.
you need to find RAM that can run at that speed or overclock RAM running close to this, hoping it will be stable.

[Jeff Harper]

Thanks Giroud. I found 4GB Corsair DDR2 1066 for $79 +free shipping. It should be here Monday! Thanks for your input.

That is the memory recommended for the board, so it's a safe bet. You were right on the money.