Is it better to have 1:1 CPU/RAM fsb ratio or quicker ram if it can take it?

norbie · 4 Sep 2007 at 15:04

Basically I currently have:

E4400 360mhz x 9 = 3240mhz

PC6400 RAM which can run fine upto 450mhz FSB.

My question is, it better to leave the ram at 1:1 so 360mhz even though it's rated at 400mhz as standard, and maybe tweak the cas timing a bit?

Or is it better to whack the ram right up and forget the 1:1 ratio?

Thanks for your help.

Marse · 4 Sep 2007 at 16:28

Good question.

The reason I'm buying PC6400 and not PC5300 Ram is so that I can use 1:1 ratio.

From what I've read the simplest approach is to use 1:1 and keep the overclocking as simple as possible for as long as possible.

Others will confirm if that logic is correct.

w3bbo · 4 Sep 2007 at 16:36

Use some tests to see what suits your pc needs better. Memory bandwidth or cpu clockspeed. I push both to the max

Yesam · 4 Sep 2007 at 19:09

Its swings and roundabouts really.

Tests show little difference, as the extra mhz, make up for the extra trips by running outta sync.

Personally? I'd run 1:1 on an intel rig, and tighten those timings!

norbie · 4 Sep 2007 at 19:14

Cheers guys, I thought 1:1 would be best.

The ram is OCZ pc6400 4-4-4-15 (default)

Running at 4-4-4-10 at the moment at 360mhz (going to raise that upto 400 probably).

Can I make the timing any better? Windows booted with 3-3-3-9 but failed on Orthos.

Meridian · 4 Sep 2007 at 21:28

To save me cut'n'pasting, take a look at my results some while ago with an E6600.

As you can see, makes pretty much no difference.

M

WJA96 · 5 Sep 2007 at 06:07

It's always worth going for the higher FSB.

The rate determining latency on most RAM is the CAS figure. This is the minimum time it takes the ram to locate a memory 'hole' on a column of memory. The RAS figure is usually less as there are more columns than rows.

The minimum time isn't the actual time, so by being able to go to the row or column more often, you have more chance of delivering the requested memory data before the next CPU cycle ticks over. It's a pretty simple calculation really. If you can, you want RAM to run 2:1, not 1:1 eg. RAM at 1066 for 266MHz CPU.

norbie · 5 Sep 2007 at 09:34

Thanks

I'm going to see if I can get the cpu FSB to go any higher, then I'll take the ram up as far as it can go. I should still be able to get CAS 4 figures on it.

Arcane · 5 Sep 2007 at 09:40

There's an in-depth guide here, kind of went over my head in places but the Excel Tool's interesting.

norbie · 5 Sep 2007 at 09:53

That looks good. I'm trying to get the cpu to 400fsb if possible. I've done it on this board before with a different processor.

What's the max vcore an e4400 can take safely?