what are some good power supply calculators. I am working on an old computer and I am not sure if the current power supply is good enough. I am hoping it is good enough because it is an older computer with a power supply they don't make anymore. those three connecters connect to the mother board. I want to know because I want to put in a pci video card. It also is a very small power supply most likely Micro atx. It as a amd k-6 and a pc133 memory up to 300mb, 1 hard drive, 1 cd drive, 1 floppy and thats all.