DDR compatibility

[Rathine]

I noticed that both DDR2 and DDR3 are 240 pin. Can I use DDR2 ram in a DDR3 slot on a motherboard if I lower the FSB multiplier speed? I didn't know if it was backwards compatible...

 

[DJDeCiBeL]

Nope. Physically incompatible because they're "keyed" differently to stop you from doing that.

 

[Rathine]

Keyed? Who would do such a devious thing? Why would they not want the slots backwards compatible with DDR2 modules?

 

[unksol]

there is no plot.... it's done to prevent you from sticking it in a slot where it wont work and could be damaged. The memory controllers, voltages, speeds, timings pretty much everything is different. basically if they hadn't keyed it differently you'd have just shoved it in there and caused problems

 

[mouse24]

Yup, ddr1 is 2.5v, ddr2 is 1.8, ddr3 is 1.5 (there are also low voltages of these ram type aswell)

Also I think you would need multiple controllers to have multiple types of ram available.

There are some boards that use ddr2 if an AM2 proc is in and DDR3 if an am2+/3 proc is in.

 

[unksol]

there's actually a few AMD processors that had both DDR3 and DDR2 controllers built in, along with the boards had both DDR2 and DDR3 slots. but yea. nothing current. that was during the switch

 

[Rathine]

So when you say "keyed" differently, you mean the little notches are in different locations, even though both are 240 pin?

I guess either way it just won't work?

 

[mouse24]

So when you say "keyed" differently, you mean the little notches are in different locations, even though both are 240 pin?

I guess either way it just won't work?

Yup, thats basically it

 

[Rathine]

So this one wasn't actually a government conspiracy, eh? He he he... Oh well, guess I'll just have to get a new motherboard and RAM. They rarely cost much, especially after I've sold the old stuff.