I am currently installing a CPU from a previous mobo to a new one. Now i dont have artic silver, can I still install the CPU without apply new thermal paste, just keep the old one on?
If it's still well-grouped and has kept its viscosity, then yes. If not, you should hold off until you can get some thermal compound.
Make sure it is thermal paste.... HAHAHAHAHAH IMHO, do not cut corners! Not worth it in the least! Just hold on untill you have new decent thermal paste. What CPU are we talking about?