Trying to understand AMD's 'Max Ram DDR/Speed'

Forums › Desktop computing › Trying to understand AMD's 'Max Ram DDR/Speed'

Batman

Mad Scientist
29769 posts

Uber Geek

Trusted

Lifetime subscriber

#28998 18-Dec-2008 19:48

Hiya all. I know that google forums say that with DDR2-667 and above, RAM is no longer a bottleneck and going upto DDR2-1066 won't give much improvement, but i am really struggling to understand my Dell AMD's lack of FSB.

In an intel unit the FSB dictates the max RAM speed it can handle.
My AMD-64x2 4200+ (2.2GHz) says it has a bus speed of 200MHz x5 to give an HT Link of 1000MHz.
Currently running dual channel DDR2-800 1+1GB and DDR2-667 1+1GB (yeah i know it's weird but upgrading small bits at a time - recently stuck in the 2 gig of DDR2-800 and kept the old ram as well).

So the question is - what is the max ram this thing will handle ie Utilise? Googling has come to a roadblock. Thanks. Just curious ... and i'm no cat!

(To cut long story short i had no hand in choosing this desktop as it was a surprise gift ... i'd have gone for Intels on an educated mobo.)

MrAlan

98 posts

Master Geek

#185506 21-Dec-2008 17:01

just think of AMD's memory link as a FSB which is dedicated to RAM.
so if you can find some DDR2-1066 it will provide you with the best performance on that board.

Ragnor

8223 posts

Uber Geek

Trusted

#185651 22-Dec-2008 11:13

DDR2-800 is much better price/performance or bang for buck than DDR2-1066 currently. The difference between DDR2-800 and DDR2-1066 is not significant, you're talking 1-3% on memory intensive operations like divx encoding.

I would sell the DDR2-667 on trademe and buy another DD2-800 1gb + 1gb kit preferably the same make and model as your existing DDR2-800

The integrated memory controller on Althon 64 X2 CPU's only a maximum of DDR2-800 anyway so even if you had DDR2-1066 it would only run at 800.

See here:
http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_9485_13041%5E13043,00.html

So anyway once you have 4gb of DDR2-800 if you're using XP or Vista 32bit then you'll want to reinstall a 64bit OS as 32bit OS's can only access around 3.x GB of memory. If you have a 32bit Vista key, you can normally install the 64bit version, you just need the media for Vista 64bit SP1

Batman

Mad Scientist
29769 posts

Uber Geek

Trusted

Lifetime subscriber

#185656 22-Dec-2008 11:43

thanks i thought so (that 800mhz was the highest supported but googling drew a blank). the phenoms would take 1066 yah.

although it doesnt actually say 1066 is not supported .... that must because there wasnt such a beast at the time of release of the statement! hmm back to square one ... no worries. will upgrade all at once when 8800gts drops in price ...

Batman

Mad Scientist
29769 posts

Uber Geek

Trusted

Lifetime subscriber

#185660 22-Dec-2008 11:54

MrAlan: just think of AMD's memory link as a FSB which is dedicated to RAM.
so if you can find some DDR2-1066 it will provide you with the best performance on that board.

what do you mean by memory link? there's no fsb ... and i don't really understand the what the hyper link is. do you have an amd-64 running 1066 ram at 533?

MrAlan

98 posts

Master Geek

#185749 22-Dec-2008 23:52

joker97:
MrAlan: just think of AMD's memory link as a FSB which is dedicated to RAM.
so if you can find some DDR2-1066 it will provide you with the best performance on that board.

what do you mean by memory link? there's no fsb ... and i don't really understand the what the hyper link is. do you have an amd-64 running 1066 ram at 533?

AMD's hyper link is a dedicated bus between the CPU and the system RAM. On intel systems and AMD systems that don't have hyper link the RAM is accessed via the FSB which means it has to share the available bandwidth with every other device in the system.

The best bang for your buck is as stated before is the DDR2-800 however it will not use the full capacity of the hyper link bus which is 1000MHz

Batman

Mad Scientist
29769 posts

Uber Geek

Trusted

Lifetime subscriber

#185766 23-Dec-2008 07:47

thanks. so when 1066 ram gets cheap we'll get some :)

Ragnor

8223 posts

Uber Geek

Trusted

#185770 23-Dec-2008 08:08

Not quite...

1: DDR2-1066 RAM will work with the Athlon X2 CPU, but it will run at DDR2-800 speed.
2: The Integrated memory Controller on X2 CPU's supports a maximum of DDR2-800 at stock FSB speed
3: For DDR2-1066 speed to work at 1006 a Phenom CPU will be needed with a newer Integrated memory Controller.

Quic Broadband

Move to New Zealand's best fibre broadband service (affiliate link). Free setup code: R587125ERQ6VE. Note that to use Quic Broadband you must be comfortable with configuring your own router.

Batman

Mad Scientist
29769 posts

Uber Geek

Trusted

Lifetime subscriber

#185795 23-Dec-2008 11:52

thanks so much for your help! i'm definitely going intel next time! not so confusing! thanks again ragnor ... i just needed to know to have some closure :)

yes i do understand that my ram is running at 667 now because it is limited by the slower one, but will eventually get it all to 800 ... having said that ram is not my bottleneck and the WEI still rates dual channel 667 and above as 5.9 so i'm not upgrading in a hurry. thanks all!

Batman

Mad Scientist
29769 posts

Uber Geek

Trusted

Lifetime subscriber

#186051 25-Dec-2008 09:57

ok so i've done more 'tests'. removed the 667 rams and ran on2x1gb ddr2-800.

as my amd runs at 2.2ghz, cpu-z says my system is running the adata modules at cpu/dram=6, @ 368MHz. now i'm losing like 32Mhz per channel. is it to do with the mobo or is the adata ram no good? also some random horizontal black lines now appear in internet explorer - i presume it's due to video card overclock incompatibility with ram. (ati x1300 594 core -> 650, 399 ram -> 526mhz; which was fine running 667 ram @ cpu/dram=7 @ 312Mhz)

there is no end to this computer tweaking business is there. *sigh

Batman

Mad Scientist
29769 posts

Uber Geek

Trusted

Lifetime subscriber

#186306 27-Dec-2008 20:11

more apologies before you hear this - i think it's still worth posting as someone else may run into the same problem.

ok so decided to upgrade to ddr2-800 ram 4x1gb. turns out that even though i bought the exact same ram, because they were manufactured 4 weeks apart, they seem to have different timings: the earlier ram has 5-5-5 and the new ram is 5-5-6. turn out, that the dell mobo can't handle the '6' in the timing so it decides to run everything at 5-5-5 @ ddr2-667MHz instead of 6-6-6 @ ddr2-800. so i'm back to square one.

will ring the shop to see if they have more 'old' ram which is faster. (i know this is nowhere near the 4-4-4s that you guys want as i have no need to afford it)

will stop trying to make the comp better. just play games on the ps3 and leave the comp alone!

(note i'd rather run 4gb ram @ ddr2-667 than 2gb @ ddr2-800 as the pagefile is much less accessed - turns out vista hates to use more than 50% of your ram and will resort to pagefile for odd jobs when you get to near 40%)