RAM Clock vs CAS?

[Trann]

I asked yesterday how i would go about changing the RAM timings of my CL 4 memory to actually be CL4 in bios.

Sure enough, my computer did not boot after i changed my ram from CL 5 to CL 4 It's running at 907 mhz CL5 atm, and can do a bit higher than that.

My RAM is 4 sticks of Corsair XMS2 800mhz CL4 1GB on a Gigabyte P35-DS4.


If i want my memory to run at CL4 i have the following options:

a) Lowering the CPU clock so that the memory clock lowers with it and reaches stable levels. Which will mean less clocked ram AND cpu.

b) Lowering the memory speed multiplier, but do that, i need to do a giant leap from 2.4 to 2! That means my memory will run at 756 mhz, which is below spec! The only multipliers availible are 2, 2.4, 2.5, 3 and higher.

Both options seem horrible to me, is it really worth the 1 less cas latency?
Or are there some tricks that i don't know about

 

[Pipe & Slippers]

You have hiked the memory voltage up to your ram's stock? - I see that some of the Corsair stuff has a range of quoted voltages (1.8v - 2.2v for yours?)

 

[Trann]

I have the motherboard set to auto regulate all the voltages, i have no idea what it's running at

Or what it's supposed to run at, for that matter

 

[RaiderX]

with performance memory you need to manually set voltages as it doesnt have them in the memorys SPD

 

[Pipe & Slippers]

I believe that standard DDR2 voltage is 1.8v so that's what you ram is currently receiving - which looks like this is lower than stock for your particular ram assuming I identified it correctly

eg. on mine I have ram voltage set to +0.3v = 2.1v = stock rated voltage - however, I've no experience of P35 bios.....

 

[Pipe & Slippers]

Look for your ram on OcUK site and see what it's rated at if you are unsure - it's often not quoted on the box/info that comes with the ram

 

[Trann]

I believe that standard DDR2 voltage is 1.8v so that's what you ram is currently receiving

Actually i don't think so, because i have the motherboard set to auto REGULATE the voltage, not to set it to factory defaults.. it works somewhat like.. the more you overclock, the mode voltage your components get.. but yes, i will try to manually specify it when i get home from work today.

But still, i'd like to know how much CAS can improve the memory performance?
To put it in rather simplish way...
CL4 800mhz to CL5 800 mhz is like.. CL5 800mhz to CL5 xxx mhz

fill in the xxx

 

[Pipe & Slippers]

beyond my knowldge mate, but I would have thought you'd want to run your ram at at least it's rated timings

re the auto regulate point, if overclocking don't set any of your voltages to auto, always define the voltages manually so you can rule out one potential reason for instability with an overclock.
I think the problem with auto in your instance is the mobo is going to assume 1.8v at stock speeds and increase it as you push your ram further which means at rated speeds it's going to be 0.3v too low, ie it's got the wrong start point

 

[Banjo]

Hi,

I've got little experience with overclocking DDR2 ram but everything is the same (in principle) to DDR.

In taking my DDR from 400MHz 2-3-3-5 (2T) to 530MHz 3-4-4-6 (2T) i recorded zero effect on read/write bandwidth from changing from CAS-2 to CAS-3, although that is only taking reading from MemTest86.

I would advise that you use a program such as MemTest86 or NuclearusMC to find the read/write speed of your ram at various settings (900MHz Cas5 and 850MHz Cas4 as a couple of examples) but I'll eat my good ol' Pentium Pro if the difference you get at the same speed with Cas4 and Cas5 is actually noticeable in any applications other than benchmarks recording read/write bandwidth

Banjo ;_;

 

[simonnance]

Cas 2 to Cas 3 is nowhere near the Cas 4 to Cas 5 diff..... the former is MUCH bigger.

Most ppl say intel systems prefer mhz over timings, so 907 @ C5 may well be faster tha 750 C4 (in fact i'd be supprised if it is otherwise). Try to push the Mhz a bit more, not sure how that ram clocks though.

 

[RaiderX]

also looser timings allow your memory to clock higher, altho your memory is rated for C4, it might not be capable of C4 at the speed you have it at