It's hard to say, Stock PSU's never are at the rated watt they have shown. That being said, why cant you upgrade? is it due to size? They make mini PSU that will fit in HP, dell cases. also make add on PSUs that go in a cd drive bay, usually 150 to 300 watts. What i used 12 years ago to power my second 7950 gx2 at the time lol