Corsair XMS memory settings

[bigboxes]

I have recently received my new motherboard, an Abit KX7-333R. My XP 1600+ cpu should arrive tomorrow from Newegg. I plan on getting a 512 stick of Corsair XMS3000 memory and then o/c. My question, "What is the ideal DRAM timing settings for this memory?" I want to set the settings as aggressive and still remain stable.

DRAM CAS Latency: 2 or 2.5
Bank Interleave: Disabled, 2 Bank, or 4 Bank
Precharge to Active (Trp): 2T or 3T
Active to Precharge (Tras): 5T or 6T
Active to CMD (Trcd): 2T or 3T

There is also DRAM Access: 2T or 3T

So, I am asking for recommendations!

 

[bigboxes]

Anyone up?

 

[CrazySaint]

Hey, dude! That memory is sweet, no higher than you're going to run the FSB, you should be able to run at the most aggressive timings.

 

[Rectalfier]

I run my XMS3000 at 167Mhz with the most aggressive timings.

 

[serialb]

Most aggressive timing IMHO:

DRAM CAS Latency: 2
Bank Interleave: 4 Bank
Precharge to Active (Trp): 2T
Active to Precharge (Tras): 6T (don't really matter, but some report 5T will do harm to your system in a long run)
Active to CMD (Trcd): 2T
DRAM Access: 2T

 

[YetiIronfst]

XMS3000C2.5, right? Not the XMS3000C2?

That means it's rated for 2:3:3 at 200MHz and will run 2:2:2 up to probably about 185MHz, maybe a bit more.

You may want to look into picking up an overclocking kit (15ish bucks) to unlock the multiplier on your XP. That way you can run the FSB at 166Mhz or higher. You'll have to do benchmarks to determine whether, for example, you're better off running at 166MHz FSB, 4:5 FSB to memory (for a 208MHz memory speed), 2.5:3:3 memory timing, or at something like 175MHz FSB, 1:1 FSB to memory, and faster 2:2:2 timings.

4 Bank interleave is supposed to be the best, although I haven't personally run benchmarks, and there are vague references to oddball situations where it can hurt performance, but for normal useage (meaning the only time a few percentage points of speed difference really matters anyway is with 3D gaming) go for 4 bank interleave.

Keep in mind that Tras is not a latency. Unlike the other values which are better off lower (2:2:2 is fastest, 2:3:3 is next, and 2.5:3:3 is slowest), this is the length of time after addressing a chunk of memory that the system can continue to access that memory before it needs to refresh the addressing. You should be able to run 6 no problem at all - the higher you crank the bus the shorter 6T actually becomes, so the easier and easier it is for the memory to perform with that setting.

 

[bigboxes]

XMS3000C2 not C2.5.

Thanks for all the advice. Any more?

 

[CrazySaint]

Originally posted by: YetiIronfst
XMS3000C2.5, right? Not the XMS3000C2?

That means it's rated for 2:3:3 at 200MHz and will run 2:2:2 up to probably about 185MHz, maybe a bit more.

You may want to look into picking up an overclocking kit (15ish bucks) to unlock the multiplier on your XP. That way you can run the FSB at 166Mhz or higher. You'll have to do benchmarks to determine whether, for example, you're better off running at 166MHz FSB, 4:5 FSB to memory (for a 208MHz memory speed), 2.5:3:3 memory timing, or at something like 175MHz FSB, 1:1 FSB to memory, and faster 2:2:2 timings.

4 Bank interleave is supposed to be the best, although I haven't personally run benchmarks, and there are vague references to oddball situations where it can hurt performance, but for normal useage (meaning the only time a few percentage points of speed difference really matters anyway is with 3D gaming) go for 4 bank interleave.

Keep in mind that Tras is not a latency. Unlike the other values which are better off lower (2:2:2 is fastest, 2:3:3 is next, and 2.5:3:3 is slowest), this is the length of time after addressing a chunk of memory that the system can continue to access that memory before it needs to refresh the addressing. You should be able to run 6 no problem at all - the higher you crank the bus the shorter 6T actually becomes, so the easier and easier it is for the memory to perform with that setting.

AFAIK, there isn't any Corsair XMS PC3000 CAS2.5, maybe you're thinking about the XMS PC3200 CAS2.5? Also, I don't think XP boards can handle the 4:5 mem ratio past 133MHz FSB, but even if they can, there's no point in it as the Athlon chips can't use any bandwidth past 1:1 ratio.

 

[FluxCapacitor]

Not all XMS memory is created equal. I just RMA'd a stick of XMS3000C2 because it wouldn't run stable at 166FSB with aggressive settings (CAS2 2-5-2 1T), which is what the XMS website claims it will run.

But, according to their website, you're supposed to be able to run this RAM at:

166MHz CAS2 2-5-2 1T -or-
185MHz CAS2 3-6-3 1T

It doesn't mention Bank Interleaving though...

But anyway, that should be the MINIMUM this RAM is capable of. Try going higher and see how it works for you.

Go here and here to check it out.

 

[YetiIronfst]

My XMS 3000C2 says it is rated for 2:3:3 at 375MHz DDR or 2:2:2 at 333MHz DDR, and that's what I'm running - 333MHz DDR, 2:2:2 - and it's rock solid.