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Greg
08-15-05, 05:01 AM
So I stuck another 512mb DIMM in my MB to make BF2 run amazingly smooth. But stupid me, I didn't first read pages 173-174 of the BIOS and Kernel Developers guide for AMD Athlon64 and Opteron Processors (http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26094.PDF) as everyone should :|. Unless I upgrade to the fancy 939 Venice core, I get to run at 333mhz with T2. (I was very confused why I could not get the ram stable until I read that DIMM support table.)

Has anyone got suggestions on how to make the most of this situation?
I was thinking of dumping the 512 modules for 2x1gb, but they might behave exactly the same according to the DIMM support table.

By the way, I ran a bunch of games and benchmarks and found that running RAM async at DDR333 degrades overall performance by 0-31% depending on application. I'm running a Athlon64 3200+ with no OCing.

Mr. Nice
08-15-05, 06:35 AM
By the way, I ran a bunch of games and benchmarks and found that running RAM async at DDR333 degrades overall performance by 0-31% depending on application. I'm running a Athlon64 3200+ with no OCing.There's no such thing a "async" with the Athlon 64 (the slow down you note is purely from the lower memory bandwidth).

Anyway, I looked at the table on pg 174 (btw, it would have been nice if you gave a page ref ;)), and I mess confess I don't entirely understand all the terminology, but I'm guessing that most "normal" 512 sticks are "x8 double rank" then, which according to the table maxes out at DDR200 for 1T, DDR333 for 2T. However, I can confidently say that table doesn't tell the whole truth ;). (Well, more precisely, it gives teh official specs so going against them is somewhat equivalent to overclocking).
This very weekend I put another 512Mb stick in my socket 754 mobo with an Athlon 64 3200+ ;) (to help out the stuttering in BF2, it worked a treat:thumbs:). It is true that it did mean I had to stop overclocking the memory so much. Previously I could run my 1gb at 230Mhz/460DDR, with 1T 2.5/3/3/6 memory timing. Now it's at 210Mhz 2T 3/4/4/8. Had to play with the multiplier stuff again to keep the CPU overclock aproximately the same ;).
It did work at 200Mhz, 1T 2.5/3/3/6 though (2.5/3/3/6 is the official timings of the memory). I'll have to do some benchmarking to see if that might be a better option, I've heard that 1T as opposed to 2T makes a noticible difference.

So anyway, long story short: Just try it and see ;). Obviously I don't gurantee it, but I'd say you have a damn good shot at still running 1.5gb from 3 512mb dimms at DDR400, although you may well have to give up the 1T timing to 2T.


Technical aside: The "FSB" (nominally 200MHz) isn't "real" for Athlon 64's. It's simply a clock setting from which all real clocks are derived. Memory is always running at an integer divisor of the CPU speed, which is "synchronous". It doesn't matter if that divisor is the same as the CPU clock multipler or not. What the bios option for DDR333 really does is choose a divisor which would make the memort run at DDR333 or less (assuming the "FSB" is set to 200Mhz, ie ignoring overclocking).

My current clock/multipler settings:
"FSB" at 252Mhz.
CPU at x10: 2520Mhz
Memory set to "DDR333", so it uses a /12 divisor (since 333/400=10/12)
so Memory at /12:2520/12=210Mhz=420DDR
HTT at x3=756hz
Note I am effecively "faking" a CPU multipler of x12, but you can't raise the multiplier of Athlon 64's, only lower it (and as at 3200+, it's rated at 2200Mhz so has a multiplier of x11).

Greg
08-15-05, 07:43 AM
...So anyway, long story short: Just try it and see ;). Obviously I don't gurantee it, but I'd say you have a damn good shot at still running 1.5gb from 3 512mb dimms at DDR400, although you may well have to give up the 1T timing to 2T...
Thanks for responding. I have already tried it at normal speeds (200mhz). With T2 set, I got 4 memory errors in 10hrs of running MemTest86+. Without T2 set, I get continuos errors. It doesn't help that I am mixing 2 brands of RAM.

Zelda_fan
08-15-05, 08:40 AM
I think the big problem is you're not running the RAM in dual channel mode (ie you have 3 sticks of ram not two or four)

saturnotaku
08-15-05, 08:58 AM
I think the big problem is you're not running the RAM in dual channel mode (ie you have 3 sticks of ram not two or four)

Socket 754 doesn't support dual channel, only 939.

john19055
08-15-05, 05:30 PM
It would be nice if the 754 had duall channel,but all of them N-force3 boards will only handle 4 banks at a 200FSB if you go over that it default to 166.But you can raise the processor speed up some like 225 and drop your multipler and run your memory at 166 and your memory should be running around 191(382),the best thing is to run two 1 gig sticks and you will not have that problem,I tried the 1.5 gig on mine but never could get it to run right so I just said the hell with it and just keep my 1gig.

Greg
08-15-05, 06:04 PM
Thanks for your replies. I am considering 2x 1gb, but according to the table in the document I referenced, it would make no difference, and would not be a gamble worth taking (unless I could return the RAM). It basically says that 2x any double sided module will require 166mhz, with a foot note that larger or more ram may be slowed further for stability. Up till now, 1gb has been fine for the desktop. Servers and workstations use different CPUs and registered memory which is much more stable for large RAM sizes.

john19055
08-15-05, 06:33 PM
The 1gig module should be a double bank and the 754 board is supposed to handle up to 4 banks and run at 200FSB,At least thats what my MSI book says.Most big computers shops have a 10 to 14 day return policy if they don't work like you want them to and then you could just take them back.