A couple of months ago I bought a new motherboard, processor, PSU and a stick of 1GB ram. I didnt know the MB was dual channel and I didnt understand the concept of it at the time so I didnt bother with getting matching pairs. Recently I ordered a matching stick which had the exact same Tiger Direct Part number. I just got it today and plugged it in and it wouldnt work in Dual channel, it works in single just fine though. I have CUPZ and the only differences that I can see are as follows: New RAM Manufacturer:"7F7F7F7F7F3E0000" Older Ram Manufacturer:"PDP Systems" Timings table for the New RAM has 3 speeds (133/166/200) and the older has 2 speeds(166/200), attaced is the .txt dump from CPUZ, please see the Memory SPD section. I called the ULTRA Tech Support and the guy said they should be compatible and he gave me an incompatibility code to return and try a different chip. I thought maybe someone here might have some info to help me. Another question, if the chips aren't compatible then should I send the older one back in the new ones package to get a more updated one, or should I send the new one back? Thanks.