Aurora R8 , is 460W PSU enough?

I'd get the 850 and be done with it, the 2060 requires 500w minimum according to Newegg. Just checked your build and think you can add 850w and liquid cooling for $150, that's what I'd select, you'd be quite happy with that setup.

I can't comment specifically on the 2060, but most of the video cards used are OEM versions and tend to not require the amount of power the full retail version uses.  Thus what configures is usually correct.

So you think that with that 460W Psu I can have problems or just I can't upgrade my pc in the future? 

Ok but I cannot be sure about that. Do you think that I can go with that Psu without problems? 

Even if the 460W PSU suffices for your current configuration, choosing that would essentially lock you out of potential upgrades down the road.  You'd end up spending more money replacing the power supply with something more capable in future. 

When it comes to power supplies, I've always advocated buying as much as you can afford now that would give sufficient headroom for expansion when needed. 

are the OEM Video card Dell uses like the single fan 2060 RTX a Good card or does it underperform then the retail card 

It's a simple blower style card. Gets the job done but don't expect Strix/ Aorus/ FTW3 levels of performance here. You'd probably want to shelf the idea of overclocking it too much. Not sure how much the power limit is set in the vBIOS.

Even retail cards have at least 3-5 tiers of performance for each brand and RTX chip. Are you looking to be ranked top N in 3Dmark/ Heaven benchmark or just don't want a lemon flagged in Userbenchmark?

Get the Power supply now and be done with it.  You will usually need a Dell replacement to make it work in a Dell/AW box.

Non Dell power supplies have been successfully used but you need sata 15 to 6 adapter for the optional optical drive.

https://www.amazon.com/CRJ-15-Pin-Slimline-Sleeved-Adapter/dp/B07FK5G2TF

EVGA 700B1 or 700BR work.

https://www.evga.com/products/product.aspx?pn=100-BR-0700-K1

However B2 B3 G2 BQ W1 N1 versions from same vendor do not work.

EPS12V with AT LEAST 150W combined on the 3.3V/5V Rails is required.

POWER SPEC

Evga with 3rd party right angle connector:

EVGA PSU

Evga g3, g5, and seasonic focus gold 850w are newer psu models that will work with the r8.  If you have the oem sata storage drive you'll also need a right angle sata cable to close the case.

I recall something about that but I thought it was brought up in reference to the sff exploding psu.   The evga g3 and g5 don't have it. 

right angle sata is not the issue I'm talking about.  SATA Power 15-Pin Male to SATA 6-Pin Slimline Power.  On some dell models right angle sata drive power is needed.

for optical is the issue im talking about.

https://www.amazon.com/CRJ-15-Pin-Slimline-Sleeved-Adapter/dp/B07FK5G2TF