the obv value depends upon how many days data you have in your pc..i know this as im having 2 pcs 1 in shop and 1 in home..in these 2 pcs whichever data say BNF, CRUDE,SILVER,NG from the same vendor differs from each other.i asked vjkris sir about this.he told this is because difference in number of days of data saved.then i cleared all data and downloaded just 10 days data in both pcs.after that OBV vallue in both pc sync.