Mix n' Match

Winters

Is it possible to mix and match differant RAM and HDD speed?

- If i have a ATA100 hard drive can i add a ATA133 Hard drive and run it at the two differant speeds or do i have to slow the second down to ata100???

- If i have 256MB ram, (in DDR-DIMM) can i add 512MB later???

BabyEater

Dunno about the hard drive but i know tou can put a 512 in with a 256

PPC

I think the pc will sort the hard drives out.
But am unsure

The ram will work if its DDR but i think it has to be the same speed ddr and is in another ddr slot. (one of the ecs boards has ddr and sd)

Quigs Snr

The ECS board in question is the notorious K7S5A, It can take SDRAM and DDR but not at the same time.


Hard disk wise, it is mostly a misconception these days that two disks on one channel at different speeds (eg: ATA66 and ATA100) will run at the speed of the lower one. Most modern motherboards (made in the past year or so) manage this themselves, so you shouldn't notice much of a performance hit.

Inspector Gadget

...if the speeds are different, the controller throttles back to the slower speed to be compatible with both RAM sticks, or hard disks, or whatever. Your ATA-133 drive will run at ATA-100 (not that you'll notice any real difference - hard disks can't actually manage to transfer enough data in a sustained way to put pressure on ATA-100 speeds anyway) and your RAM will run at whatever the lowest speeds is (say PC1600 or PC2100, or whatever - I assume they're both the same over type, i.e. both DDR, or both SDR etc.?) depending on the boards themselves. The actual capacity of each disk (or RAM module) is pretty much irrelevant in most modern boards these days.

Gadget

Winters

If i get 1 256MB PC2100 DDR and 1 512MB PC2100 DDR will they work on the same motherboard is my question?

First time i installed ram into a pc if you mixed the 8mb with the 4mb that was in the 486Machine it wouldnt work...

Has this changed since the old 486days?

Ruaidhri

Originally posted by Winters
If i get 1 256MB PC2100 DDR and 1 512MB PC2100 DDR will they work on the same motherboard is my question?

First time i installed ram into a pc if you mixed the 8mb with the 4mb that was in the 486Machine it wouldnt work...

Has this changed since the old 486days?

woah! things have changed since them
the problem you had is you are supposed to install simms(Single Inline Memory Module) in pairs for them to work.

now we have dimms(Dual Inline Memory Module,guess what?)
you CAN install mix and match the memory of differant capicaty as long as they are the same clock speed(1) and same amount of pins etc..

1)of course you can over clock/down clock...

po0k

SIMMs for 486s didn't need to be installed in pairs.

Don't ask me why, I never had one (started on Pentium100), but I remember reading it on a ad for Crucial or Kingston ram or SMC or some such.

Gerry

It depends purely on the bus of the machine. My 486 didn't need simms in pairs, but some did afaik.

About your ram, well it depends what speed ram your motherboard needs. You can put in an extra dimm without a problem, and it doesn't have to be the same capacity. If you put in a faster dimm, it will quite happily run at the slower speed. It won't try to force the whole lot to run at the faster speed or anything. Putting in a slower dimm ( eg pc1600) into a board which is trying to run the ram at pc2100 will cause problems of course.

Quigs Snr

Most early 486 machines, didn't require memory to be put in pairs. This became more widespread with the advent of the Pentium processor and 72pin EDO RAM.

Inspector Gadget

In terms of a little background, maybe this will be helpful:

SIMM = Single Inline Memory Module
DIMM = Dual Inline Memory Module

SIMMs have a 32-bit-wide data bus, which means that data flows in and out of them four bytes at a time. DIMMS, which for all intents and purposes are two SIMMs stuck back-to-back on the same circuit board, have a 64-bit-wide data bus.

Now, all x86 CPUs up to (and including) the 486 had a 32-bit-wide data bus, whereas the Pentium upwards has a 64-bit-wide data bus.

Because there was a crossover period where Pentium CPUs were being used with SIMM memory (I have one at home, I know...) the solution the chipset manufacturers used was to use the SIMMs in size-matched pairs, and the memory controller on the motherboard would convince the CPU that it had 64-bit-wide modules where it actually had pairs of 32-bit-wide modules...

Now, if you stuck two mismatched SIMMs into adjacent "paired" slots, the memory controller couldn't figure out how to slice and dice the data being read and written; (a common approach for this type of module pairing was to store odd bits on one module and even bits on the other) so the BIOS tended to report it had bad/no memory and the machine wouldn't boot.

These days, however, the bus width of the memory modules again matches the bus width of the CPU, so "pairing" is no longer necessary... for now. However, as far as I remember, this shouldn't be a problem with 486s - they only had a 32-bit-wide bus, same as the SIMMs?

Hope this helps,
Gadget

Gerry

Nah, this pairing of modules is still going on. Rambus modules are only 16bit, and are paired to give 2 channels.

Dual ddr, when it arrives will require paired modules.

Inspector Gadget

Originally posted by Gerry
Nah, this pairing of modules is still going on. Rambus modules are only 16bit, and are paired to give 2 channels.

Dual ddr, when it arrives will require paired modules.

Wasn't aware of that - must read up on the subject (not done much with Intel kit in a quite a while, and there aren't a whole pile of AMD/Rambus combos out there )

[edit]Although, on reflection, there's always n-bank interleave, NVidia's TwinBank and so on...[/edit]

Cheers...
Gadget

Gerry

Yeah I had forgotten about the nforce, mainly because the extra bandwidth it requires is not used by the athlon, unless you steal some of the cpu's bandwidth with the onboard graphics. Nforce for the p4 would have been great, but we'll just have to wait for intels and vias solutions.

Winters

Well. Im not too worried how it went back in the old 486days.. (Thought today i found my old 486, removed the processer and ram.. and put em back in, i doubt it works)

I bought my motherboard: Abit KR7A-133
And i bought Ram: DDR-DIMM PC2100 for PC266MHz

Hopefully they should work and ill be happy once they arrive (Ordered them last night)