Don't know if this is the right forum, but...I want a memory upgrade and I know nothing about memory. I rebooted my Dell Dimension 4550, went into the BIOS menu, and looked up the memory type: 512MB DDR SDRAM, 266 MHz.

Then I went to dell.com and searched for parts using my machine's "service tag". It offers me 512MB DDR SDRAM, but 333 Mhz, not 266 MHz.

So I have two questions: why are my BIOS and my computer's manufacturer telling me two different things?

And does it matter if I have two different memory chips, one 266 MHz and one 333 MHz?

Thanks.

And does it matter if I have two different memory chips, one 266 MHz and one 333 MHz

No you can't have PC2100, PC2700, PC3100 mixed. They all need to be the same.

If you want to add memory and you have an open slot then put in more of the same kind as you now have in the first slot.

If you want to remove what you have and put new RAM in, and your chipset supports faster memory then yes put in whatever you want. The Chipset determines how much and what kind of RAM you can install on the mother board.

I have before put PC133 into a older MB and run it at PC100 and it works ok. PC133 won't work in a PC66 machine though. I don't know if you can get away with putting in PC2700 and running it as PC2100 or not. If it works it will run at the slower speed. You can't put slower RAM in a spot made for faster RAM, it won't work.

Best bet would be to put in what you have in now unless you see that it is supose to be the next speed.

Either way don't mix them.

Thanks!

You can mix memory speeds but the slowest memory will be the maximum speed the FSB will go at. For a 333 MHz bus, you will need DDR400 memory because of real environments deteriorate the memory from the clock, voltage, and heat. Yes, memory can be underclocked and it is better that you do because it lasts longer and it is more stable.