While I'm sure a destructive lunatic could force a DDR module into an older slot, they are not designed to be physically compatible. DDR modules have only a single notch, while SDR modules and slots are keyed with two notches and ridges.
No.
No.
No.
No. SDR SDRAM and DDR SDRAM modules are not interchangeable.
The number of pins at the bottom of the stick. Some ddr's have 184 pins, some newer models have 240, starting with DDR2.
Motherboards of that era would have had a either a combination of the older SDR SDRAM (PC100 or PC133 RAM) and DDR SDRAM, or just DDR SDRAM.For best performance, you would want to use the DDR slots.
DDR and SDR have the names mentioned on the packing.You just need to read the packet.But if you don't have one then try reading on the ram chip you will find small initials on chip saying DDR with its number.
Depending on its age, either SDR SDRAM, DDR, or DDR2 RAM.
DDR SDRAM (Double Data Rate Synchronous Dynamic Random Access Memory) transfers data twice per clock cycle. It achieves this by transferring data on both the rising and falling edges of the clock signal, effectively doubling the data rate compared to single data rate (SDR) SDRAM. This allows DDR SDRAM to provide higher bandwidth without increasing the clock frequency.
DDR, DDR2, SDR, DDR3, DDR4. SO-dimm are for laptops
PC133 Ram and PC333 ram are generally incompatible. PC133 RAM is SDR Ram where as PC333 is DDR RAM. Some motherboards support using either SDR or DDR but this is not usual. PC133 will not fit in the same slot as PC333.
If the motherboard supports both DDR and SDR RAM, it is almost always a better idea to go with DDR RAM