sdram and dimm whats the difference

  bigboab y 10:13 11 Jun 2004

Trying to add 64 megs of memory to a Siemens Scenic 300 base unit.(64 megs installed).. I bought a 64 meg meg sdram on Ebay, put it in and nothing happened..i.e no boot up (the strip was sold to me as working) main question is whats the difference between 168 pin sdram and dimm i.e are they in any way compatible .. could someone point me in the right direction..pretty please

  Graham ® 10:40 11 Jun 2004
  Eric10 10:43 11 Jun 2004

Physically, SDRAM has two notches where it plugs in while DDR ram only has one and they don't line up, so unless you use force they don't fit into each other's slots. Even if your motherboard had both types of slots you can't mix them. Have you tried the new memory stick on its own? It may just be incompatible with your existing memory.

  norman47 10:51 11 Jun 2004

sdram stands for Single Data ram, ddram is Double Data ram and a dimm Direct Inline Memory Module is a generic name for ram. lesson over. lol

Sdram comes in 3 basic speeds 66Mhz, 100Mhz and 133Mhz. The trouble is that it is then sub divided in to single sided and double sided modules ( sticks of ram ).

This is further complicated by EEC ram( error checking ram ) and non buffered ram. EEC ram has a dedicated chip on the dimm that checks the data and is used mainly for servers, but will work in a lot of machines. Non buffered dimms check the flow within the memory chips and are most common to home computers.

If this was not enough then it is sub divided again by C.L. ( class latency ). The standards are 3.0, 2.5, and 2.0. 2.0 is the newest and fastest, 3.0 is the oldest and 2.5 is the most common used.

So if you can understand the above, I have difficulty lol, then you will see that sdram does have a lot of variations. Sdram is backwards compatible so 133Mhz will work in a 100Mhz machine.

Unless you know the exact specifications of the new and the old ram, it is difficult to see if they are compatible. one of the troubles is that people are getting rid of the EEC SDram and this will not work in some machines or is not tolerable with non EEC ram.

I would suggest you take out your original ram and try the new ram module by it's self. If it boots then find out the specifications by using aida or belark advisor.

Sorry if this is long winded, but you did ask.;-)

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