CM Extreme Plus 500W unit is low quality PSU and i would not buy it. If it's used, it's even worse,
review:
https://www.hardwaresecrets.com/cooler-master-extreme-power-plus-500-w-power-supply-review/
Looked at Pakistan PC stores and found a good quality PSU with great price. PSU in question is FSP Hydro GE 650W (80+ Gold) and it costs only 10.200 Rs,
link:
https://www.shingpoint.com.pk/power...650w-80-plus-gold-full-modular-power-supply-2
review:
https://www.tomshardware.com/reviews/fsp-hydro-g-650-power-supply,4462.html
While the 650W unit is a bit much for GTX 1060, it is well enough to power RX 580, which is 185W GPU, compared to the 120W GTX 1060.
I looked at several stores and in other stores, there were worse quality PSUs with higher price (e.g in another store, Corsair TX550M was at 12.000 Rs).
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
You can cheap out on every other component inside the PC
except PSU. Also, while the PSU warranty covers the PSU itself and you can RMA the blown PSU, the PSU warranty doesn't cover any other component the PSU fried.
Most people learn the hard way not to cheap out on a PSU when low quality PSU blows and takes part of the system or the whole system with it. Question with low quality PSUs, especially with used PSUs, isn't
if it blows up but
when it blows up. Even entire houses have been burned down because of the fire low quality PSU caused when it blowed up.
If you cheap out on PSU now, you'll save 7.700 Rs, right? 7.700 Rs saved now can cost you 50.000 Rs when the (used) CM Extreme Plus 500W unit blows up and fries your entire PC. No matter how i look at it, 7.700 Rs extra is far smaller sum to pay for good quality PSU than 50.000 Rs for a completely new PC.
Like it or not, if you want your PC to work for years to come without any risk of fire and/or damage to your components, you need to hand out some money for good quality PSU. I'm not talking that you need to go with the best PSU money can buy, e.g Seasonic PRIME 650 (80+ Titanium), which costs $150+ (21.250 Rs) and which also powers my Skylake build. FSP Hydro GE 650W i linked above costs 10.200 Rs and is more than enough for your PC, both wattage and build quality wise.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Also, like i said, Xeon E3-1240 V2 is equal to i5-6600 and 6th gen Core i5 is not a weak CPU. I have i5-6600K with GTX 1060 3GB and i have no bottlenecks in my PC.
About RAM. Like i said, you may face issues with 8GB but that doesn't mean 8GB won't work. It works fine and i understand the choice of going with 8GB rather than 16GB.