Depends on the i5 model, but generally id expect 250 cad for decently new i5 and board, 500 to 600 for that 1080, like 20 for the hdd (i recommend not selling a hard drive though unless youre really thorough wiping it clean!!), 8gb ram is like $80, arctic cooling fans are dirt cheap, case toss another $50 depending on the model, and rgb add another $30 to $100 depending how extensive it is.
Overall a quick nonspecific estimate: $1050 CAD or about 700 usd. Personally id go to pcpartpicker.com and list EVERYTHING in the pc (fans, coolers, even the cables) that will be going with it, and chop off about 30% to account for age and wear. Aios will boost the price. Full loop will add hundreds, good cable management is free and may speed the sale. People dont just want functional, they want pretty too We need specific details and pictures to give a better estimate