Can you use ddr ram on your computer that is using sd ram?

Not both at the same time. Most motherboards will be able to support both types of RAM but DDR RAM is much better, due to the double data capability it has. Since RAM prices are quite cheap it would be better if you throw out your SD RAM and buy DDR. No you cannot use both ddr ram and sd ram on the same pc. You have to use either or depending on the motherboard. The slots are different. You can determine what type of memory you have by entering setup in the biOS when you turn on your pc. DDR Ram has a slot in the very center of the chip that forms to the slot you plug it into. SD ram has a slot on the chip off set the middle. Hope this answers your question. No you cannot use both ddr ram and sd ram on the same pc. You have to use either or depending on the motherboard. The slots are different. You can determine what type of memory you have by entering setup in the biOS when you turn on your pc. DDR Ram has a slot in the very center of the chip that forms to the slot you plug it into. SD ram has a slot on the chip off set the middle. Hope this answers your question