Could i mix DDR 2 800 memory with DDR2 667 Memory or would the pc kick off just wanted to know if i could get away with it or is it better to stick with the same MHZ

Cheers

You could run the 800 underclocked as long as it's not in the same banks as the other DDR speed, but if you're buying the stuff new, I'd either buy the total amount as the faster RAM and flog the old stuff, or buy matching speed RAM.

It's easier to not try and mix as the results can be unpredictable.

You can use RAM which are different speeds, the system steps all RAM down to the slower speed, so if you have an 800 module and a 667 module then both sticks will run at 667.

There really isnt much point in overclocking RAM not unless you are building some sort of Uber rig. Make sure you have the latest bios update and just alter the settings in the bios for which your ram is best suited.

You can use RAM which are different speeds, the system steps all RAM down to the slower speed, so if you have an 800 module and a 667 module then both sticks will run at 667.

There really isnt much point in overclocking RAM not unless you are building some sort of Uber rig. Make sure you have the latest bios update and just alter the settings in the bios for which your ram is best suited.

You might think that RAM can just under clock itself fine, but while the speed might be the same the timings and latency can differ when RAM is under clocked and you get some very weird behaviour. Sometimes it's fine and sometimes it will work but be unstable.

Ive never personally had any issues doing it. I upgrade DDR1 laptops and PCs all the time and most of my customers have less than DDR400 in thier PCs/laptops eg 266/333 etc and normally I add a 1GB DDR400 stick to thier old 256/512 stick which is running at a lower speed.

Never had anyone come back saying thier system was unstable or doing anything untoward.

Sometimes you can have incompatibility between different manufacturers of ram modules though, normally I use Kingston, Transcend or Corsair RAM and 1 of the 3 works with whichever ram happens to be in the system as stock.