The exact software I would not trust. Avast just causes problems with literally everything. CCleaner is useless and has minimal benifits. I dont trust these magic PC doctor apps. Try chaninging your powerplan and/or using a bootable USB to test it
SLI causes lesser 1 percent low fps and is not worth the money. Just sell both cards and get a better one. Sell both 1060s and get a 5700 and a better CPU
I would not trust vinegar in my loop due to risk of corrosion (and it stinks). Just buy the ant-microorganims stuff and flush your loop every 6 months to a year. Also use distilled water instead of pre mix as it corroded the parts less