I added 2 additional sticks of PC133 memory to a Soyo SY-6BA+IV MB and it causes 2 different games to lock up whereas with only 2 sticks the games were alright. I ran 2 different memory testing programs (Doc Memory V2 and Mem386 Test V3) over 24 hours with each program and everything passed! I tried the 2 additional sticks by themselves and all was fine. I tried the 2 sticks in slots 3 & 4 bythemselves and still fine. All sticks are PC133 I believe (not all the same manufacture), though the MB is PC100. I then tried one additional stick and it was a borderline case. The games would usually work but with a struggle. As I was just over the limit. The P/S is only a 250W, but the Porcessor is only a PII 450! Nothing overclocked! The videocard is a nVidea GeForce 2 MX from IO Magic (not great). The games are Scrabble Complete (runs from the CD) and Trainmaster V4.2 (runs from the HD). Desktop is 1024x768 high color 75Hz. The O/S is Win 2k w/sp3. It seems either the system has a limit of 256 or maybe a P/S issue, BUT all tests pass. Especially after 24 hours in the extended mode (I think that was what it was called).