If you are not planning on building a PC soon, I would go with a cheaper and less powerful GPU than the 1660Ti (like a 1060, a 1060Ti or maybe the 1070). You can get these cards way cheaper even when buying them new (if any shop has these on stock).
The reason I would go with a less powerful card is: even the RX580 is a huge overkill (which is weaker than the 1660Ti) for an x1 PCIe lane (and the wireless mPCIe slot uses an x1 configuration). Basically the GPU will need the power, will work on it's max, but you wont get those nice and high FPS numbers, because the x1 will bottleneck it (imagine a 16 lane road - that's the GPU - cars are fully using all the 16 lanes, and then suddenly the 16 lanes narrow to 1 lane...).
But you can hook up a 1660Ti, - I haven' tried it, but it should work fine - just think about wat I have written before
And I didn't change anything in the BIOS, but I highly recommend checking out this article, if you haven't already 😉
P.S.: I am planning on replacing my X550JX's board with the same board as yours, because why not, and if it won't work out, I will use that board as a desktop PC... Or I'll sell it
@botond_boldizsar, Thank you so much for your response and valuable information. Yes, as I've been researching, although a GTX 1660ti might work I won't benefit from it's full potential so I'm considering a GTX 1060 or GTX 1070. With either of those, what performance do you think I'm looking up to, 60 - 70% more or less??
@carlos_daniel_hernandez, According to my experiences, around 60-70% is what you would get... And sometimes less, sometimes a bit more, depends on litteraly everything.
Hi @esteban_santana_vazquez, (checked with Win+R then typed msinfo32) my BIOS is in UEFI
@botond_boldizsar,Thank you, because my asus g750jx has win 10 in legacy mode and it gives me error 43 when it detects the rx 580 by means of a hotplug. It seems to me that I will have to reinstall win 10 in UEFI mode for it to be detected.
İt would be great if u help me here guys,
I have Asus X550J without (x) ended like on topic model.
Specs: İ5 4200U 2.5 ghz, 6 gb ram and 2 gb gtx850m graphic card.
By the way I dont have external monitor!