3 ram sticks and two memory channels

[vazel]

when you have 2x256mb and 1x512mb does it matter how it's placed? would you want to have both memory channels even? putting 2x256 mb in slots 1 &2 and putting the 512mb stick in slot 3?

 

[maaoouud]

Simply put: if the 256 modules are single sided (only have chips on one side of the module) and the 512 module is doublesided you want to put the 256 modules on one channel and the 512 on the other to load the memory controller evenly. This may not actually be the case, but in all other cases it wont really matter how you place them anyhow (closer to the chipset/controller is often best though).

EDIT: Of course, if one 256 is doublesided (DS) and the 512 and other 256 is singlesided you put the DS on it's own channel. Didn't even occur to me at first as I assumed you bought matching modules

 

[Deathlike2]

It matters to memory stability and clock. If your mobo enables dual channel memory, then having an odd number of RAM is BAD by far. You need to read your mobo's manual and see if this is the case.

Some mobos have issues having 3 sticks of DDR installed (like in the case of the K8T800 and NForce 3 based chipset, they both happen to be able to hold 3 DDR sticks max). There is a fair chance that you will have reduced, if not crippled performance in doing so. If you don't care about performance and care more about capacity, then you still may want to test for stability with Memtest86.

Also, note that double sided memory (those that have memory chips on the front and back) have a greater chance of preventing you from reaching optimal memory speeds (and ultimately performance).

Oh.. and memory placement does matter... especially in mobos/cpu combos that use dual channel memory. You need to look in the manual to see what the ideal placement for the RAM is to achieve the highest performance.

Hope this helps you. You are much better off having 1GB of memory in the form of a pair of 512MB single sided memory sticks than what you currently have.

 

[Cartoon Corpse]

i have (antique) 1G rdram (pc800)..

how much faster (in general) is current DDR2 ram than my antique...20%...2x...3x...10x.. 1000x?

im curious, just popped into my head. sorry if it annoys.

 

[Deathlike2]

i have (antique) 1G rdram (pc800)..

how much faster (in general) is current DDR2 ram than my antique...20%...2x...3x...10x.. 1000x?

im curious, just popped into my head. sorry if it annoys.

I have no idea, but RDRAM has high latency which would hinder performance to some extent. RDRAM has high clock speed to compensate (800MHz, someone feel free to correct me if I'm wrong here.) DDR2 is low latency, but has a lower clock. Performance is very much limited the the low frequency it runs at...

How much really depends... particularly whether dual channel is employed... but it doesn't matter in my opinion.. I think DDR2 is the way to go simply because of cost. I can't stand the ligitation RAMBUS keeps going through for $$$.

 

[Kurt]

Some mobos have issues having 3 sticks of DDR installed (like in the case of the K8T800 and NForce 3 based chipset, they both happen to be able to hold 3 DDR sticks max).

Actually, Socket 939 boards do have four slots, older 754 boards have two or three, eg.
Asus A8V (K8T800) -- 4 x DDR-DIMM
DFI LANPARTY UT nF3 Ultra -- 4 x DDR-DIMM

Three sticks probably means dual channel will be disabled (Asrock 939DUAL-SATA2 does that for example).