Effects of Memory Speed on CPU Overclocking

[Jephph]

I know that memory speed typically doesn't make huge performance difference by itself, but how much higher a CPU overclock can you get with say, a DDR2 1333 set compared to a DDR2 800 set?

 

[Gillbot]

If you are fsb limited in your overclock, stepping up to a faster set of ram can lift that restriction. My old OCZ PC2-6400 (800fsb ram) limited my OC to 400fsb, with my new Buffalo Firestix PC2-8500 I got 500fsb easily.

 

[DSF]

There's no fixed answer to this question. Sometimes it won't matter at all, and sometimes it will make a big difference. Is there a particular CPU you have in mind?

 

[LOUISSSSS]

you will need the higher ram speed if your motherboard's FSB goes past that ram speed. (assuming your ram cannot overclock)

for example

u have DDR2 800 ram (400mhz effective)
you have your e8400 overclocked to 400 x 9 = 3.6ghz and you want more
you try 450mhz and your pc freezes.
you are either FSB limited or ram speed limited in this case.

 

[Jephph]

Let's say the Q9300 (2.5GHz, 1333 FSB) So would that essentially be 333 effective FSB * 7.5 multiplier to get the 2.5GHz? So then with DDR2 800 RAM (400MHz effective) you could raise the FSB on the processor to 400 easily to get 400*7.5= 3.0GHz?

 

[DSF]

Originally posted by: Jephph
Let's say the Q9300 (2.5GHz, 1333 FSB) So would that essentially be 333 effective FSB * 7.5 multiplier to get the 2.5GHz? So then with DDR2 800 RAM (400MHz effective) you could raise the FSB on the processor to 400 easily to get 400*7.5= 3.0GHz?

Yep, that's how it works. If you want to push that chip past 3 GHz you'll need faster RAM and a motherboard that can handle running the FSB that fast.

(On the other hand, some quality DDR2-800 modules will overclock well past DDR2-800.)

 

[Jephph]

10 4. Thanks for the info:thumbsup:

 

[UpstartXT]

Originally posted by: DSF
There's no fixed answer to this question. Sometimes it won't matter at all, and sometimes it will make a big difference. Is there a particular CPU you have in mind?

Well I hear the best option to go with for gaming is the e8400, so that's the one I'm thinking about.

In reply to those talking about memory latency, I was referring to RAM capacity, as this is what I am changing as stated with the original post. If I have a stable overclock at 8 GB, will going down to 3GB mess me up?