Thanks guys for enlightening me. Obviously my understanding of the matter was minor! I have given up on the idea of buying the R9 280x forever because of its age, its power consumption and especially that the seller is advertising gpu risers. This says a lot.
As for the RX 460 and why I want to replace it while that step seems to be useless under the current platform; I'm actually have a compatability issue running the RX 460 [UEFI only] with the Asus p5q-e [Legacy BIOS] my bios was choppy and laggy and windows takes ages to boot up) but once It boots up everything is working fine. I also have tested it on another old asus AMD board and it's got the same problem while working perfectly on my friend's asrock z97! So I decided to sell it and I managed to sell it two days ago for 170$ to a noobish minner who went crazy after watching it hit 13.5mh/s eth (I unlocked it and modded its timings)
Then I had two choices.. Gtx 770 and 960 both 4gb and for the same price 160$ while gtx 1050 ti is flying in the sky with 250$ (used) so I went for the gigabyte gtx 960. It performs similarly to the gtx 1050 ti and consumes less power than the GTX 770. It's really in a good condition and I'm happy with it.
I'm not sure what country you're from which actually makes giving an answer harder..
It's Egypt where there's a financial crisis after floating the exchange rate. A few months ago 1$=7EGP, now it's 19EGP! Whatever money you have, it have been cut-down by more than the half, the hardware market is insane and completely a mess so upgrading the entire platform now is a waste of money and would give a miserable price-performance ratio, that's why I'm trying to give that old rig the kiss of life. I agree with the guys here, I should upgrade the whole system instead of the gpu but maybe after a couple of years when the economic conditions stabilize.