View Full Version : OT: Computer Memory (RAM) -- help

05-05-2007, 12:46 PM
Sorry about the OT post .. since I've seen quite a few computer questions come up, there must be people here that know stuff about it. :)

Trying to upgrade my computer memory.. hoping to get a computer guru to lend some insight -- because my system keeps crashing.

my motherboard has 4 slots on it for memory.. my manual says i have to put them in in balanced pairs. i've been working with 1gig (2 x 512 modules).. and since the price seems to have dropped, and i've been doing more drawings on my computer, i bought 2 more 512 meg pieces.

If i put in the old pair: everything works fine
if i put in the new pair: everything works fine
if i put in both pairs (4 x 512meg): my computer has brainfailure and hangs.

i've inspected the modules closely, and the only inconsistency i can find is this:

two pairs read: DDR400(2.5)
two new pairs read: DDR400(3)

I can't find info anywhere on what that number in parenthesis means.
or if its the cause of my problems. anyone know?

any know if i'm supposed to do something else other than just plug them in?

any help would be great

metal content: I'm taking the modules out with a dent puller.

05-05-2007, 02:25 PM
IIRC, those numbers indicate "CAS Latency". But normal memory spec has more than just that, so not sure about the notation. Basically, the new memory is slower than the old memory. You should be able to set this in the BIOS at boot time. I doubt you can set it per bank, which means you'll need to set it for the slowest memory.

More info (http://www.tomshardware.com/2002/05/07/perfect_timing/)

05-05-2007, 02:30 PM
Another article for your reading pleasure. (http://www.tomshardware.com/2004/01/19/ups_and_downs/page3.html)

05-05-2007, 04:18 PM
What motherboard/BIOS do you have? If you can get the two pair to work together, it'll probably be because you tweak some RAM setting in the BIOS setup menus (hit some key combo a few seconds after power-on before Windows loads up.) Probably you need to increase the timing values, depending on what the BIOS setup menus will let you do.

I have a pretty fancy motherboard which has probably 50 settings for RAM. It was pretty confusing even for a computer nerd like me to figure out and get it tuned up. The first thing I ran into was Windows XP x64 (shouldn't have gotten x64) would not deal with one of the settings which has memory working on both rising and falling signal edges (can't remember the name of it.)

05-05-2007, 06:21 PM
hrm. i haven't thought about BIOS settings. I just figured I could plug these things in and vrooom. i've got an old foxconn board.

baddog-- that article was completely over my head. but i wanted to ask.. if i do set these bios settings.. which one is slower "2.5" or "3"? and will it actually be using those numbers in my BIOS? or is it going to ask me for something crazy.. like a frequency or voltage or pressure or temperature or relative humidity?

you guys might be getting an idea about how much I know about this stuff.

again, any (more) help would be greatly appreciated. I'm reluctant to make a blind bios change in fear that my machine just will never start again.

right now i'm back to the old ram, 1 gig, and running fine. my new ram is right here next to my coffee cup.


05-05-2007, 07:00 PM
Most boards with 4 slots will have a seperate controller for each pair, so as long as each pair of slots has one type of memory in them, they'll work.

normally your slots will be different colors, put the new ram in one pair, and the old ram in the other, if not switch slots, put your slow ram in the primary slots, which -may- be configured to set the speed.

My system runs fine in dual channel mode with 3 gigs of unmatched ram, (2x512+2x1g different brands) but with another pair I had that matched the 2x512 it would only beep on bootup.

there are issues with cheap ram on some boards, relating to density of the chip

Check your bios version, then the motherboard makers website to see if they have a newer version out to address any ram issues, my original ram problem was fixed with a later bios, but by then I had already exchanged the ram.
also, see if they have an approved vendors list for ram, pretty much just a list of ram that is KNOWN to work with that motherboard.

If that doesn't help, I'd say pose the question over here,


most guys there are fairly knowledgeable, and should be able to come up with a better solution.


05-05-2007, 07:08 PM
ken, thanks.

after baddog put me on a dangerous road frought with reading, i made some bios changes. most made bad things happen.

then i set everything to "Auto" and dropped my ram speed down from 400mhz to 333mhz (or 323, something 3--) .. and now i'm up and running.. seems stable.. no crashes yet.

windows tell me i have 2 gigs installed now.
www.crucial.com has a tool that i ran .. it tells me i still have 1 gig.

looks like it might be time to drop this thing off somewhere.

my saturday disappeared just like that!

thanks again all.

05-05-2007, 07:10 PM
It should be labeled as "CAS Latency", or maybe "CL", or something that should ring a bell. It will be in a section labeled something like "Memory" or "Chipset Features"

Good point, you may need to "flash the BIOS", which is basically just installing a new version. Check the mobo manufacturers web site for details and options.

05-05-2007, 07:14 PM
Not sure about that Crucial tool. If you run TaskMan and Physical Memory reports as 2GB, I would say you're good to go. But you might want to start trying to creep up on the clock speed to the rated values. It can get tedious, but you should be able to get it to run at the rated speed of the slowest (the one marked (3)) at least.