Incorrect RAM timings from SPD?!

[sleepyhead]

Abit FP-IN9 SLi mobo
Corsair XMS2 PC6400 (800Mhz) C4 DHX, 2GB. 4-4-4-12

Any reason why my mobo would automatically specify the timings to be 5-5-5-18?! Or is the mobo just showing that as it's currently set to auto in BIOS?

Another question..before I change the timings to 4-4-4-12, should I try it at 1T and ramp the voltage up to the 2.1v that is on the label?

[Fabula]

SPD gives out safe settings, and the standard settings for PC6400 are 5-5-5-18.

Corsair have specified it to run at faster timings, so just set it manually in BIOS.

[Sema4]

Just wanted to confirm that Fabula is correct, my corsair RAM does this too, it's normal, it defaults to slower, safer timings, to guarentee the system will boot, just change it in the BIOS.

[sleepyhead]

Ahh..well that explains it then

Previous RAM I have used (Corsair DDR XMS stuff), the mobo picked up the right timings from the SPD

But should I ramp the voltage up to 2.1v like it says on the DIMM or leave it at the current auto selected BIOS setting of 1.85v?

[BUFF]

if you are setting the tighter timings then increase the RAM voltage to the specified level too.

[Sema4]

As I understand it, it's the motherboard/BIOS that reads the SPD then backs the timings off a little, this is probably most useful for those that like to over clock and who push the timings too far while trying to find the limit...

I suspect it's motherboard dependent as to whether it will back them off a little, or not... some boards will, while some won't, either way in my experience, it seems to be normal behaviour for the very high spec motherboards that people like to over clock.

If I was in your shoes, and it said '2.1v' on the DIMM, then I would ramp it up to that, I trust the people that make it to know what they are talking about lol.

[BUFF]

if you use something like CPU-Z to show the SPD table you'll see that the SPD timing is probably programmed with looser timings than the manufacturer's advertise.
All the mobo is doing is reading that SPD table & setting those timings.

[Sema4]

CPUz shows my corsair exactly at rated spec, 2-3-2-6 but if I boot with my ASUS board on 'auto' then it never comes up with those timings, they are always slower... If I put the ram in another board (MSI K8T Neo) then it boots at 2-3-2-6 on auto, it's just the ASUS board that slows things down leading me to think it's board/BIOS dependent :shrug:

[BUFF]

some mobos have Auto & "by SPD" as options

[sleepyhead]

Poking around the Corsair site, you guys are right on the ball. Designed to boot at 5-5-5-18 but tested to run at 4-4-4-12 @ 2.1V

I believe that my mobo doesn't have SPD, just AUTO and MANUAL hence it defaults back to the JEDEC (is that right?) settings.

Woo hoo, tighter timings here I come...well eventually once I get home from work.