Yes, the type could affect it, but your machine should give you some sort or error if that is the problem. When the chip is in, run a memory diagnostic from the CMOS (you usually have to hit DEL or some key right after the machine comes on to get into the CMOS) and see if the memory is being detected properly.
The only type issue I can see you having is if you are mixing and matching sizes of memory chips (for ex, 2 512MB and 2 256K chips), or if some of your memory is ECC and some isn\'t. ECC is a type of memory that sacrifices some speed for 100% reliability.
Personally I\'ve found that 1GB is about all a GigaStudio machine needs, because with that many instruments, I am running into the 160 voice polyphony limit. I need to upgrade to a 2 machine system.
Some motherboards have timing problems when you fill more than two of the RAM sockets. Check with your motherboard maker for info/limitations and check other web sites related to your motherboard for similar problems and fixes. I\'ve seen this kind of a post on overclockers forums and your problem may not be software related.