256MB turns turns to 128 MB on asus

**dirkpitt** · April 13th, 2003, 03:11 AM

hi ya'all,

I'm just wondering how come, a 256MB Pc133 Ram on an unknown AMD XP motherboard turns to 128MB when I try it on my Asus P2-BF motherboard.

any ideas? I'vce tried changing the manual settings for SPD on bios, but still the same.

I have 1 kingston 256, and 3 128 sticks of an unknown PC133 Ram. total = 655MB on existing system.

I tried replacing the unknown PC133 256MB on every slot, and all registered 128MB on my asus board. very weird! since there are no errors.

anyway, thanks for any comments.

BTW, do you know of an app that can detect RAM brand and or specs without opening the case?

**confus-ed** · April 13th, 2003, 05:07 AM

Its all this slot/banks business that's causing confus-ed-ness

Your 256 changes to 128 because your asus board can only 'see' half of it, your other board can see all of the memory (1 slot usually is two banks)...

If you look at any slot 'head on' the left side connectors are usually considered bank one, the right side bank two, so three slots for instance is generally six banks ... this depends on the design of the motherboard...

At a flying guess the memory module you have has all 256 in one bank, for it to work correctly on that particular Asus board you need RAM that has a maximum of 128 per bank, so you want a double sided stick with 128 in each bank, for single sided ram your board has a maximum mem capacicity of 384 (3x128) but to use all the maximum 768 you need 3 double sided 256s (128 on each side)...

This is further complicated by the fact that visual inspection isn't enough - for memory to be 'double sided' it needn't be actually double sided it needs to have the memory 'wired' into seperate banks ... very confus-ing

If the memory in question is the same speed at the others it'll probably work just fine as a 128 ... but you wanted 256 like it should be...either swap it or find a motherboard with a 256 bank limit (So you want one that takes 512 in any one slot -bank/slot again!)

**dirkpitt** · April 13th, 2003, 06:06 AM

that's probably it. visually the 256 stick in question is double sided, but 256 might be on one bank only.

my kingston 256 ram is also double sided, but is detected as 256.

**Matridom** · April 13th, 2003, 07:53 AM

Originally posted by confus-ed
Its all this slot/banks business that's causing confus-ed-ness

Your 256 changes to 128 because your asus board can only 'see' half of it, your other board can see all of the memory (1 slot usually is two banks)...

If you look at any slot 'head on' the left side connectors are usually considered bank one, the right side bank two, so three slots for instance is generally six banks ... this depends on the design of the motherboard...

At a flying guess the memory module you have has all 256 in one bank, for it to work correctly on that particular Asus board you need RAM that has a maximum of 128 per bank, so you want a double sided stick with 128 in each bank, for single sided ram your board has a maximum mem capacicity of 384 (3x128) but to use all the maximum 768 you need 3 double sided 256s (128 on each side)...

This is further complicated by the fact that visual inspection isn't enough - for memory to be 'double sided' it needn't be actually double sided it needs to have the memory 'wired' into seperate banks ... very confus-ing

If the memory in question is the same speed at the others it'll probably work just fine as a 128 ... but you wanted 256 like it should be...either swap it or find a motherboard with a 256 bank limit (So you want one that takes 512 in any one slot -bank/slot again!)

I'm impressed Confus-ed, I knew the issue, i knew what caused it, but did not know why it was caused.. thanx for the explanation.