reddevilman

Hi, looking to upgrade the memory in an old desktop,have done a orca memory test and it has told me that the motherboard has four memory slots,I have opened the case and can only see two slots,the ram installed is as follows samsung 2 sticks of pc2700 256mb ddr 184 pin the orca scan says that there is four slots so im buggered, i aint computer savvy so any help would be greatful