I have a server motherboard with dual socket 604 using, I believe, single core Xeon CPU's. I would like to upgrade to quad core Xeon processers if possible. Will any socket 604 processor work? What are my options?
Your option is to find exact MB model number and look at it docs or vendor support site for exact Intel Xeon CPU numbers/models supported. Socket 604 has long life with several generations of CPUs for it, there was VRM differences, FBS differences, so first S640 MBs will not support late S604 Xeons