I have a question maybe someone can help me with. I have one of the original K7 .25 microns die size CPU's. I want to upgrade my CPU, but am unable to find any .25 size CPU's anymore now that they are all .18 in size. My question is, will a .18 CPU fit in my Motherboard? My motherboard is rated for 300mhz more then what I have in there now, and I would like to upgrade.
Yes, there were .18 micron Athlons (Thunderbird) manufactured for Slot A. I have to assume, since you say your motherboard will support another 300MHz, that you currently have a Athlon 700. A quick check on Pricewatch revealed that a 1GHz Slot A Thunderbird is selling for almost $300.00. You would be better off replacing your motherboard with a newer KT133A chipset board and a Socket A CPU. It'll cost you about the same price as a 1GHz Slot A T-bird and you'll have an upgrade path. Also, you must have an AMD750 chipset on your motherboard to ensure reliable operation with a 1GHz Slot A T-bird.
It's not worth buying a new processor for your board. Upgrade to a socket Athlon.