Hello im looking to upgrade my 250w psu in my hp p6120f to a 400w-500w psu. From everything that i have read so far i have seen that new hp's are made to work with most atx psu...and also that they have different video power connectors. I am just confused and new to the world of upgrading. the size of the current psu in my system is depth- 4" height 2.5" and a width of 5". any suggestions? i would like to get something that would work for it right out of the box.(would be nice) thanks for the help : )