Can i use 30% isopropanol to clean my cpu?

Best - Indigo Extreme Cleaner - about $6

2nd best - 99% Isoprophyl alcohol

3rd best - 91% Isoprophyl alcohol

Whatever isn't alcohol is something else and the something else leaves residue on ya CPUs, GPUs etc.

I use the Indigo stuff .... few ounce bottle has lasted me thru about 8 water block installs and have about 3/4 of it left