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All right, folks, I am humbling myself before the GameBanshee tech gurus and asking what the hell is the difference between the different kinds of DDR memory?

Everyone seems to have a different standard of DDR RAM which start at PC1600 and go up to PC3500. If I buy an Athlon XP motherboard that takes up to 3 DDR memory chips and uses a 200/266 MHz front side bus, what advantage do I get from buying a 256 MB PC3500 chip for $90 as opposed to a 256 MB PC 1600 chip for $50?

Will I see a qualitative amount of increased performance by going with the more expensive chip? (assuming all other things are equal).

Originally posted by HighLordDave
Will I see a qualitative amount of increased performance by going with the more expensive chip? (assuming all other things are equal).

In a word, yes.

I will put in more on Sunday. One other thing to bear in mind is your motherboard has to be able to support the higher speed of memory, there is no gain if your DDR chips are set towards the higher speeds if your mobo can't take the strain. Much like having a new Radeon 9700, without a 8x motherboard Although i do think it is more important than that and the memory stick wont actually work unless it is the correct speeds...i might be wrong on that though.

Will higher-rated DDR memory work in boards that only support lower-rated DDR memory?

For instance, if you have a Intel board with a 100 MHz FSB, you can put PC133 memory in it and it will function fine. However, you if you put PC100 memory in a 133 MHz board, it won't work.

Similarly, if my board supports only PC2100 DDR memory, will I see extra performance by buying PC2700 DDR memory?

Originally posted by HighLordDave
Will higher-rated DDR memory work in boards that only support lower-rated DDR memory?

For instance, if you have a Intel board with a 100 MHz FSB, you can put PC133 memory in it and it will function fine. However, you if you put PC100 memory in a 133 MHz board, it won't work.

Similarly, if my board supports only PC2100 DDR memory, will I see extra performance by buying PC2700 DDR memory?

Basically, no. The memory speed is dependent on support from the chipset. Unless you have a very new board that utilises PC3500 DDR memory you won't gain any performance advantage over PC2100. You'd be better off looking for memory that supports a faster latency timing that more bandwidth. CL2 memory tents to be a bit more expensive (and in this counrty rarer) that CL2.5 or 3, but the improvement is worth it.

As a side note, most VIA chipsets support asynchronous mode, but the AMD 760 chipset doesn't. If you tried to put DDR266 or 333 memory onto an AMD based board running a DDDR200 CPU your system will drop down to DDR200 spec.

Here are the specifics of my problem:

In a rare lapse of judgement, my wife turned me loose with the check book to buy the parts to put a new computer together (an early birthday present). I picked up an Athlon XP 1800+ CPU, MSI KT3 Ultra motherboard, 256 MB of PC2100 DDR RAM and a Visiontek Xstasy GeForce4 Ti4200 video card. Everything else I had lying around the house and I am putting it together today while I clean off my old computer to give to my wife and the kids.

The motherboard, which uses VIA's KT333 chipset, supports PC2700, PC2100 and PC1600 DDR RAM. The computer store I bought it from only stocked PC2100 DDR RAM. I am wondering if I should take the chip he sold me back and get him to order some PC2700 DDR RAM for me, or if I won't notice any difference in performance.

EDIT-I got my machine put together today and I have a question about the CPU clock speed which may be related to my DDR memory. The Athlon XP 1800+ should run at a clock speed of 1.53 GHz, yet when my machine boots, it shows a core CPU frequency of 1150 MHz. Could this be due to the PC2100 (266 MHz DDR memory) I have? If I get PC2700 (333 MHz DDR memory), will I get the full 1.53 GHz CPU clock speed?

EDIT2-Forget what I posted in the above edit. I broke down and read the manual which said that MSI boards ship with a default FSB of 100 MHz. If you want a higher core clock frequency, you have to manually change it to 133 MHz (or whatever). My CPU clock frequency problem was not related to the DDR memory, but I am still wondering if I should get PC2700 DDR RAM for this machine or if the PC2100 will be sufficient for my needs.

By the way, thanks to Mr Sleep and Mr Flibble; and thanks in advance to anyone else who might be able to help me on this.

Originally posted by HighLordDave
Here are the specifics of my problem:

In a rare lapse of judgement, my wife turned me loose with the check book to buy the parts to put a new computer together (an early birthday present). I picked up an Athlon XP 1800+ CPU, MSI KT3 Ultra motherboard, 256 MB of PC2100 DDR RAM and a Visiontek Xstasy GeForce4 Ti4200 video card. Everything else I had lying around the house and I am putting it together today while I clean off my old computer to give to my wife and the kids.

The motherboard, which uses VIA's KT333 chipset, supports PC2700, PC2100 and PC1600 DDR RAM. The computer store I bought it from only stocked PC2100 DDR RAM. I am wondering if I should take the chip he sold me back and get him to order some PC2700 DDR RAM for me, or if I won't notice any difference in performance.

You lucky sod!

RAM is cheap, so I say do it anyway. I'm not sure exactly what extent the difference will be, but faster is always better.