FSB and mixing DDR
 

Afternoon folks.

One for those with a bit more knowledge on FSB and DDR than I have at the moment. I've been having a sniff around the internet but just can't find the exact answer to my question.

I've got an aging PC at home which has an Athlon XP 2100+ (Palomino, 133MHz core) and 512MB of PC2100, 266DDR RAM. I've recently purchased some PC2700 333DDR RAM (2 x 512MB) but not 100% certain if it's okay to mix the 2 types.

I picked up the PC2700 after I read an article on DDR RAM and Athlons -- where the feature said the Athlons had a core of 166MHz... which is correct but for some of the more recent chips and not mine. I found this out after buying it but the glass is half full as the PC2700 was cheaper than PC2100 anyway.

Running my PC with the 266MHZ CPU and 333DDR seems fine and is quicker than before given the hike in RAM value... but can I assume that although my motherboard reports the RAM running at 333MHz that it in fact will drop and match the CPU's 266MHz..? Or will the RAM run at the faster speed and leave the CPU to be a bottle-neck..?

I have the option of putting both types together to give me even more RAM value but not sure if it's recommended. I've got a copy of SiSoft Sandra and have been doing some crude benchmarking -- 1GB of mixed RAM does seem to score less than 1GB of the 333DDR... so it's possible I've answered my own question but would value any comments from those with experience.

Trying to work out if my PC will be quicker with 1.5GB of mixed or 1GB of 333 only (but Sandra fails to benchmark when I put the whole lot together.)

Cheers,

Jonts.