PC2-6400 VS PC2-5300 Different Slot Sizes? Tags: Memory RAM Last response: October 21, 2012 6:41 PM in Memory Share thoreaubakker October 20, 2012 11:11:33 PM Greetings. 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! Thoreau More about : pc2 6400 pc2 5300 slot sizes pcnut2001 October 20, 2012 11:34:17 PM I have 6400 running just fine in my pc wich orginally had 3200 thoreaubakker October 21, 2012 12:04:47 AM 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. Thanks! Related resources D630 pc2-6400 vs pc2-5300 - Forum 2 gb pc2-5300 vs 1 gb pc2-6400 - Forum PC2-5300 vs . PC2-6400 benchmarks (in a C2D)? - Forum PC2-6400 (800MHz) running at pc2-5300 (667MHz) - Forum Upgrading PC2-3200 to PC2-5300 ???? - Forum Can't find your answer ? Ask ! Get the answer anort3 a c 149 } Memory October 21, 2012 12:22:28 AM DDR, DDR2 and DDR3 are all keyed differently and will not fit in each other's slots. http://tinyurl.com/8f4nobx ( ^ 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: http://en.wikipedia.org/w/index.php?title=File:Laptop_S... 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. thoreaubakker October 21, 2012 5:19:09 PM 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 -t. anort3 a c 149 } Memory October 21, 2012 6:41:25 PM Yep that would explain it! Oh well glad you figured it out. Can't find your answer ? Ask ! Publish Related resources 4GB 2x2GB doesn't work with 2GB 2x1GB kit well ? Forum PC2-6400 vs PC2-8500 Forum Help On Choosing Graphic's Card. Forum Ram problems/cas Forum 4GB x2 +1GB x2 will I get dual channel? Forum Can I use my old HP pavillion case to build a new desk top? Forum GeForce 210 vs GeForce 8400 GS Forum Server - currently Celeron 1.8 -> what Xeon should I get? Forum Building new system.. Nvidia 8600GT? Forum "Reboot and select Proper boot device" Forum Can i use PCIe3.0 slot in PCie 2.0 mod? Forum Asus M2A-VM HDMI Memory Slot 4 problem? Forum Issues with unused memory slot Forum Memtest shows different RAM settings for Channel A&B, for same stick. Forum Different RAM will it work? Forum More resources Read discussions in other Memory categories Compatibility DDR2 DDR3 Dual Channel RAM Corsair G.SKILL !