PC2-6400 VS PC2-5300 Different Slot Sizes?


I bought a 4 gig kit of Crucial Ram yesterday at Futureshop.

My computer manual said it supported 4200 and 5300, but the guy at the shop said I could use 6400
and it would just run at the slower rated speed.

The thing is, when I went to install it, it wouldn't fit on the mother board.

I pulled out a stick of the 5300 that's in the there now, compared the new ram and old ram, and clearly
noticed the slots are different.

I tried googling but couldn't find an answer.. My last question on Tom's hardware (in prep for this purchase)
was not answered.. If some hero would answer this one I'd be very grateful.

Question is: does 5300 and 6400 always have different slot sizes, or is there two different profiles for DDR2?

to confirm, both the old and new sticks are DDR2, and my searches didn't lead me to anything mentioning
different slot sizes.

Thanks all!

5 answers Last reply
More about 6400 5300 slot sizes
  1. I have 6400 running just fine in my pc wich orginally had 3200
  2. Thanks for the reply pcnut2001.

    Do you have any tips or things to trouble shoot?

    Is there any other differences in ram that you know of?

    Again, I'm talking about a mechanical issue here, preventing

    me from even trying to install it.

  3. DDR, DDR2 and DDR3 are all keyed differently and will not fit in each other's slots.


    ( ^ link fixed )

    PC2 4200 is DDR2 533, PC2 5300 is DDR2 667 and PC2 6400 is DDR2 800. These should all be compatible and fit in the same slots.

    Any way he gave you laptop memory? It would look like this:


    Now the very first DDR3 was DDR3 800 and was written as PC3 6400. That would be very old and uncommon DDR3 but if it's not laptop RAM that's all I can think of. Make sure it's not DDR3.
  4. anort3,

    thanks very much for the response!

    I wasn't laptop memory (I'm not THAT dense ;) but I do appreciate the suggestion.

    After much searching, I found out the problem.

    My system (a Dell Precision 490) is a workstation, and only takes fully buffered EEC memory, which I guess seems to have different slots, even though it is DDR2.

    Who knew?

    Now off to take back this ram and start hunting for the stuff I need.

    Thanks again :)

  5. Yep that would explain it! Oh well glad you figured it out.
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