To be honest and frank, that's 5 year old tech and not worth much more than 6-7k. You also have to consider that PC parts depreciate relatively fast over time. A PC that was worth 15-20k 5 years ago will only be worth 7k now (if that).
The other thing is, when and where/from who, did you buy this? If you paid 20k for it recently, then you got scammed.