should i update my graphics card ?

Solution
Should is one question; what to is another.

If you are not getting the performance you want then it is time to upgrade.
If your limitation is graphics you can upgrade to a stronger graphics card.
It is recommended that such an upgrade be a big one, three tiers higher or you may be disappointed if you do not see big results. That would be a GTX970 class card. GTX1060 is even better.
A psu that can power a GTX760 can run a card as good as a GTX1070.


Should is one question; what to is another.

If you are not getting the performance you want then it is time to upgrade.
If your limitation is graphics you can upgrade to a stronger graphics card.
It is recommended that such an upgrade be a big one, three tiers higher or you may be disappointed if you do not see big results. That would be a GTX970 class card. GTX1060 is even better.
A psu that can power a GTX760 can run a card as good as a GTX1070.


 
Solution

Yes, but there are better choices.
That card has fancy coolers for which you pay a premium.
It has a clock of 1506 and a boost clock of 1708 for $295 after rebate
http://www.newegg.com/Product/Product.aspx?Item=N82E16814126114
compare that to the simpler EVGA SC for $260 with a clock of 1607 and a boost of 1835
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487261

What is the make/model of your psu?
Any R9 card is more power hungry, the 390 should have a 650w psu.