What happens when ram is fater than cpu

Mycobacteria · Aug 30, 2007

I have Corsair 6400 C4 RAM running at 400 (x2)
I have a CPU at 200 (x4)

Thus my ram is running twice as fast as my CPU ie a FSB to DRAM ratio of 1:2

1 Does this mean that there are wasted cycles on the RAM?

2 Is there ANY advantage at all in for havin RAM running faster than the CPU?

3 Should I lower the speed of the RAM to try and gain 3.3.3.8 T2 times?

jason4207 · Aug 30, 2007

It's hard to say. See how tight you can get the timings stable at the highest speed, and run some benches. Then reduce the speed and find the tightest timings at that speed and run the benches again. Use whatever benches better!

You can also try all the RAM multipliers in-between 1:1, and 1:2..it will take some time, though.

orion456 · Aug 30, 2007

Mycobacteria said:
Thus my ram is running twice as fast as my CPU ie a FSB to DRAM ratio of 1:2

There is no practical advantage to run anything other than 1:1. At that setting your FSB is moving data as fast as the CPU can accept it and as fast as the RAM can send it.

Faster timings will help a bit, but the default settings work just as well within a few percentage points. It's not really worth the bother and the possible instability.

jason4207 · Aug 30, 2007

orion456 said:
There is no practical advantage to run anything other than 1:1. At that setting your FSB is moving data as fast as the CPU can accept it and as fast as the RAM can send it.

Faster timings will help a bit, but the default settings work just as well within a few percentage points. It's not really worth the bother and the possible instability.

I tend to agree, but some like to run their RAM faster. At least get the tightest timings possible at 1:1 ratio, though.

Yellowbeard XMS · Aug 31, 2007

In the testing I have personally done, some applications benefit about 2-5% from having the memory running faster than the CPU. However, as software becomes more able to multi thread (ala quad core CPUs) the extra bandwidth will have more real world benefit.

One Bull · Aug 31, 2007

Jup, somehow faster memory helps, especially on C2D's. But you shouldn't sacrifice you cpu oc for the fastest ram speed.

Personally I always bench every memory divider when my cpu oc is achieved

dogbert_2001 · Sep 2, 2007

Your FSB is actually 800.

Automata · Sep 2, 2007

dogbert_2001 said:
Your FSB is actually 800.

Uhh...no...he has it at 200, it is in his first post...

jason4207 · Sep 2, 2007

FSB800 is effective speed due to it being quad-pumped. 200 is what the clock generator is running at.

What happens when ram is fater than cpu

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