Some motherboards do work well with a mixture of PC100 and PC133, others do not like the different types being mixed at all, and it can cause problems. You are right if PC100 and PC133 is mixed and works fine, then the system will run as if both sticks are PC100. Before you replace the PC100 with PC133, you need to make sure the motherboard runs PC133, as it may be cheaper and easier to just put a new stick on PC100 in instead. As not all motherboard will or do run PC133, so it would see and use it as PC100, but again thee could be some problems too. W98 does not like more than 512mb of ram either, that is the same for W95 and ME too. W2K and XP will sue what ever you can give it, especially for heavy graphics and video files etc. Trevnal ----- Original Message ----- and one I really should remember the answer to.. A friend has asked me to give her PC a checkover. Everything is (now) running fine but she is a bit light on RAM (64mb). I have checked the memory stick and it's The SIMM PC 100 type. Now, am I correct in saying that I can put in a PC133 stick alongside this, but the new memory will only function as PC100? Or, would it be better to dump the 64mb PC100 stick altogether and replace it with PC133 only? Also, does W98 have a maximum amount on the amount of RAM it will recognise? Cheers Andy To unsub or change your email settings: //www.freelists.org/webpage/pctechtalk To access our Archives: http://groups.yahoo.com/group/PCTechTalk/messages/ //www.freelists.org/archives/pctechtalk/ For more info: //www.freelists.org/cgi-bin/list?list_id=pctechtalk