I have a computer that uses pc2100 ddr sdram memory and I want to upgrade it. I was wondering if it mattered if i got pc2700 even though my motherboard says pc2100. If you can does that mean the memory won't be running at full potential and at pc2100, or can u even do this. Also i was looking at the memory on the web and sometimes they give the speed 100/133 and sometimes it is with pc2100, this is confusing because I dont know if 100/133mhz is pc2100.

Thank You for your help

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Yes it actually does. Each RAM module is rated in Mhz (Megahertz). PC2100 is rated at DDR (double data rate) 266Mhz and PC2700 is rated at DDR 333Mhz.

If you buy PC2700 and plug it into a board that runs PC2100 only...it will default down to the PC2100 speed...and that would beg the question 'why'.

For a great article on RAM, try http://www6.tomshardware.com/motherboard/19981024/index.html



To further answer your question...PC100/133 is only single data rate ram. It runs only at 100Mhz and 133Mhz respectively. So DDR would be twice the speed but actually increases the memory throughput a bit more than that. The article above


thanks you've answered my question, so you can buy say a pc2700 and it will work for a motherboard that supports pc2100.

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Yes...PC2700 will work in a PC2100 only board...but would be a waste IMHO


Don't mix types of RAM...say, having PC2100 256MB and a PC2700 256MB...mainboards often get confused with this.

Mixing different speeds of RAM can work just fine - mixing brands is another story! You've also got to ensure that both sticks can run at the same memory timings (timings are basically an indication of how fast a stick of RAM responds to, say, a request to transfer some data - the lower the better).

You might also find that PC2100 and PC2700 RAM is more expensive than PC3200 (or the price difference is very small), being outdated and all. A PC3200 stick would work just fine, and you could carry it across to a new system in the future if you so desired.

To further confuse you, PC2100 DDR RAM actually runs at 133Mhz, but due to the way Double Data Rate RAM works (2 operations per clock-cycle), it's rated at 266Mhz. PC2700 runs at 166Mhz, which is effectively 333Mhz.

Onya, Coco. Let's obfuscate matters, eh? :lol:

What motherboard do you have, please, and what processor?

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