How important is a 1:1 RAM ratio?

[Dougx1317]

A few months ago I was reading a forum about memory ratios. I remember that the target memory ratio is 1:1. I bought new RAM for my laptop with a T7300 processor with a 800Mhz bus. The new RAM is 667Mhz, so the ratio turns out to be 5:3. My monitoring program confirms that it is running at 667Mhz with a RAM ratio of 5:3. Is this bad? Does it slow down my system? Is it even possible to change it? There's no options in my bios.

My RAM: http://www.newegg.com/Product/Product.aspx?Item=N82E16820104033

 

[gamerk316]

Technically, what happens is that your RAM can send data faster then the CPU can deal with it (or vica-versa, although that doesn't happen often...), so it has to wait for the CPU to send a signal. This does take some time, but it is usually minimal.

This is how you get 1:1:

Take your FSB (800) and divide by 4: (800/4 = 200)
Take your RAM speed (667) and divide by 2 (667/2 = ~334)

To run at 1:1, you would need to downclock your RAM to 200MHz, or OC your FSB to (334*4 = 1336) MHz.

As you can see, even though 200MHz DDR RAM would run at 1:1, the loss in speed would cause you to run slower as a result.

There are cituations where a 1:1 RAM ratio is faster (667 DDR2 with a 1333 FSB can be slightly faster than using 800MHz DDR2), but it usually isn't a huge jump.


In short, if you can get 1:1, great. Otherwise, its not that big a deal.

 

[Dougx1317]

Why do you divide the FSB by 4 and the RAM by 2? Would 400Mhz RAM work just as well as 667Mhz RAM? Would downclocking my RAM to 400Mhz be a good thing to do?

Being a laptop, I have no control in the bios. Is there anyway to change it through Vista? I'm a guy who likes to get every last inch out of his computer. Do you know any programs that could safely OC my FSB? Or will it really not make any difference?

 

[cjl]

I wouldn't worry about it. The difference is not worth bothering with, especially on a laptop.

 

[Dougx1317]

Thanks for the information.

 

[Wolfshadw]

theres no such thing as 400 for ddr2. Its 533, 667, 800, 1066....

Actually, there is...

Newegg List for DDR2-400

-Wolf sends

 

[kg4icg]

here is my system running at 1:1 and yes I have speedstep enabled

now of course it depends on the setup you have and how far you can push the motherboard for in which mine is a Gigabyte GA-EP45-DS3L which can go to 1600 on the fsb