Ram's almost impossible to tell who the manufacturer is. Sometimes a place such as Crucial will have a sticker on it with their name, but usually there ie nothing. Not even looking at the chips will tell you, many companys such as Samsung sell chips to even more companys to use.

RAM is simple - if it works, it's good, if not it's not, or at least not compatable. PC100 and PC133 is a big difference. Most 133 is backward compatable to 100, but not all. It usually just doesn't show up as being installed at all, but it's possible it would cause this type of problem instead. PC100 won't handle the PC133 speeds either.

I think you need to decide which stick(s) of RAM work, and at what speed. Then just get more. Even the ones that don't work may not be faulty, just not correct for the application.

Also - beep codes can generally be deciphered. You probably have an Award or Phoenix BIOS, perhaps another. A google search with your codes - track the number of long and short beeps, should tell you why the board is hanging up. However, NO beeps usually has to do with the CPU. Either it's dead, or maybe the motherboard requires a fan to be plugged in to cool it (the CPU), and one is not.