Memory compatibility?

[Monkey34]

This might be a dumb question, I dont know. I've always kept the right memory on my boards, but am wondering if DDR acts like plain sdram in this regard - you know how if you have a pc133 mobo, you can use pc100 or pc133( it just runs at 100)? does DDR do this(put ddr2100 on a board that takes 3200 for example - and it will run on the slower speed)? Does it work the other way around (ie: buy faster memory, and have it run at the slower board speed)?

 

[Sirje31337]

To my knowledge. If your mobo only supports, say, PC2700 it won't run anything higher then that. I doubt it would work.

 

[Monkey34]

Found this in the faq:

Memory is very much similar in this way. Many people ask if a PC3500 or PC3700 module would run/blow up/be compatible in a motherboard originally designed to use PC3200 or PC2700. The answer is, hell ya! JEDEC (the “government”) has only approved PC3200. This reason, coupled with the fact that no processor needs memory rated higher than PC3200, are causes for motherboard manufacturers not stating support for newer, faster modules. But higher rated speeds of DDR are always ‘backward compatible’ so to speak, or capable of running at lower speeds. Older systems stand to gain from newer and faster modules. Even if they can't run the module at its top supported frequency, you can still tweak the timing parameters to maximize performance at lower clock speeds, that otherwise would not be possible with lower-rated modules.

Faster memory + slower mobo = ok
slower memory + faster mobo = Burnt electronics.

Now to go shopping!

 

[burningrave101]

You can use any speed of DDR you want. You need the RAM to be at least fast enough to match the FSB otherwise your system will have to run the RAM alot slower to work. You can put PC4000 in a 333FSB Athlon board but there wouldn't be any point in it. If you dont overclock just buy the RAM the same speed as your FSB. If you do overclock its best to buy a little faster.

 

[KevC]

Originally posted by Monkey34
slower memory + faster mobo = Burnt electronics.

Now to go shopping!

Not necessarily Since you have PC2100, you could run whatever your next processor is at 133MHz FSB. You could get a cheap board with a 2400+ since that's 15x133MHz.

But PC2100 is pretty much obsolete, you can get cheap PC3200 anyway

 

[Monkey34]

But PC2100 is pretty much obsolete, you can get cheap PC3200 anyway

Thats pretty much the way I was thinking. Why be stuck buying more 2100, if I see a good deal on another speed? I think I'm gonna move on up to 1g of mem.