Managed to pick up a 1.8 Dothan pretty cheap. It's used so it has no thermo pad. Question is can I use some Artic Silver paste that I already have or do I need a thermo pad to fill a gap? If it has to have a pad does anyone have a cheap source? TIA...
I would use the Arctic Silver (AS), AS5 if you can get it.
If what you describe as thermal pad is the thin tin foil and gray gum found under a heatsink, then you don't need it at all.
If you have it, remove the tin foil and clean all gray gum from both the heat sink and the CPU chip.
For cleaning, use 91% rubbing alcohol if you can get it, other percentage alcohol have a higher H2O content leaving more moisture behind.
Don't use your uncovered fingers to touch either the CPU or the heatsink bottom or to spread the AS. Fingers leave minute amounts of human oil which help promote heating, not cooling.
Apply a thin layer of AS ontop of the CPU pad itself (where the CPU lettering is visible), as smoothly as you can, do not goop it on. More is not better in this case.
Remember when the heatsink is applied, it will spread the AS over the remaining empty pad of the CPU.
I usually make a miniture box shape, about as evenly as I can (well, sometimes), then I let the heatsink pressure do the rest.
My testing has found better cooling using the method above, rather than using the manufacturer thermo pad gum, although I've seen literature saying the opposite.
Hope this works for you.