single sided vs double sided memory cards ?

[rbutcher]

I rearranged the memory sticks on my boxes, and then I noticed that the performance on my main box, Linux on a AMD 2.2 ghz, had become sluggish. I have 2 x 512 mb ddr 400 sticks in it, but I see one is single-sided and the other is double-sided. Does this meam they are not compatible ? What do I need to look for when using 2 sticks together ?
thanks
Rod

[IronBits]

Rule of thumb is to use identical memory sticks.
The single sided runs cooler...
Not sure if you are running into an interleave or timing problem...
In dual channel mode, matching DIMMs need to be used.
Watch for cas latency, as a 3 means 3ms, while a memory with a cas latency of 2 (2ms) will process data 33% faster.

Another interesting thing I found out, using google of course...
A single sided DIMM counts as one bank, a double sided DIMM counts as two banks. It only really matters if the motherboard you're putting the DIMMs into has a limit on the number of banks of RAM it can see, for example, if a board has 3 DIMM slots, but can see only 4 banks, you can only use 2 DIMMs if they're double sided; you can use 3 DIMMs if two of them are single sided.

Check to make sure your system is reading all the memory... you may have put that much in there, but the mobo might only recognize 1/2 of it...

[LAURENU2]

I beleave I read somewhere that addressing memory above 512 with more then 1 bank will take 8 to 10% off the read/write speed.
So if you want 1 G mem do it with 1 stick is best

[rbutcher]

Rule of thumb is to use identical memory sticks.
The single sided runs cooler...
Not sure if you are running into an interleave or timing problem...
In dual channel mode, matching DIMMs need to be used.
Watch for cas latency, as a 3 means 3ms, while a memory with a cas latency of 2 (2ms) will process data 33% faster.

Another interesting thing I found out, using google of course...
A single sided DIMM counts as one bank, a double sided DIMM counts as two banks. It only really matters if the motherboard you're putting the DIMMs into has a limit on the number of banks of RAM it can see, for example, if a board has 3 DIMM slots, but can see only 4 banks, you can only use 2 DIMMs if they're double sided; you can use 3 DIMMs if two of them are single sided.

Check to make sure your system is reading all the memory... you may have put that much in there, but the mobo might only recognize 1/2 of it...
Thanks for this. How do I identify the cas latency, is it written on the chip ?

[LAURENU2]

Thanks for this. How do I identify the cas latency, is it written on the chip ?
Today 08:40 PM

Ya that is what I always wanted to know to
It mad me mad at the Mem makers that I could never figure out there code:swear:

[IronBits]

Thanks for this. How do I identify the cas latency, is it written on the chip ? No, but the manufacturer number will give that to you when you look it up.
Give me the specifics on the following and I'll see what I can come up with.
mobo(make/model/version)
ram(anything you can give me)
Back in the old days, I could tell what they were by the numbers stamped on each chip, but not any more...

[rbutcher]

Thanks IB.. I could only find a cas marking on one stick, it is 3. I reset the box so it had 2 x single sided sticks and performance appears to have improved.
You mentioned motherboard.. are you saying that I need to find out what cas latency its chipset supports ? Presumably then it's no pointing having really gonzo memory if the chipset doesn't upport it ?
I can look up the specs on the Via website.

[IronBits]

Some mobos won't work, or work well, with single and double sided sticks together (mostly older ones)
The mobo manual should tell you what memory is recommended for each one.
Sounds like you solved the problem tho.

[PCZ]

Are you running an xp 3200+ ?
In a motherboard with an NFORCE 2 chipset ?

If you are then you managed to go into single channel mode.
Dual Channel is much faster.
The post screen will tell you if you are running single or dual.

On the NFORCE 2 boards you have 3 ram slots, two together and one seperated a bit from the other 2.
This is often a different colour.

You put a simm in the slot on its own and another one in either of the two slots which are together to run Dual Channel.

They have to be the same capacity to work together as Dual Channel.
So 2 256's or 2 512's but not a mixture.

You can cheat a bit and use 3 simms and stay in Dual Channel.
Use 2 256's in the 2 slots which are together and one 512 in the slot on its own.

The above only applies to NFORCE 2 chipsets.
Intel and the AMD A65 MB's use a different simm layout.
They have 4 simms slots.