THE POWER SUPPLY UNIT

 “Does a PSU really matter? Do I really need a branded PSU in my system?”
Oh lord.
A power supply unit (PSU) is the single most important yet neglected component in a gaming PC. The habit of disregarding such a key component started from the time computer casings came free with cheap low quality PSUs which apparently were made to “do the job.” This stands true for PCs that don't quite excel in the performance department. If you're running one of those PSUs in a gaming PC, then you are doing nothing but digging your own grave.
Reasons why you should consider a branded PSU:
Efficiency: Power supply efficiency is defined as the amount of power actually provided to the internal components, divided by the amount of power drawn at the wall. A 50% efficient PSU that's tasked with providing 50W of power to a system will draw 100W from the grid. The extra 50W is lost. So in theory a 90% efficient PSU would draw 56W, hence saving you bills and keeping it all cool under the hood.
Failsafes: Good PSUs are usually equipped with a lot of failsafe technologies the likes of Over Current Protection (OCP), Over Voltage Protection (OVP), Under Voltage Protection (UVP), Short Circuit Protection (SCP), Over Power Protection
(OPP), Over Temperature Protection (OTP), Surge & Inrush Protection (SIP) &No Load Operation (NLO). Tl;dr: this means your PSU will keep your PC parts healthy and safe from the evils of unstable electricity.
Upgrading: For PCs equipped with high-end  external graphics cards, a good PSU is an absolute requirement. PSUs have certain rails called the 12V rails, these rails power the CPU and GPU simultaneously. Generic Chinese PSUs have low 12V rails, hence they are incapable of outputting their rated power. These are not recommended, as they can, and most probably will burn your GPU.
Before you buy:
Thermaltake makes decent PSUs, just make sure you don't go for Thermaltake Litepowers for builds with high-end GPUs. Thermaltake Smart and Toughpower are both capable PSUs with varying wattage capable of handling any gaming PC with ease. Corsair's CX line up is also good as well as the high-end HX and AX.
InWin recently introduced some units and as far as the reviews go, these are capable PSUs. Avoid all Gigabyte units, as they are more often than not very unreliable.
Cheap generic PSUs like Delux and Value Top are no different from generic Chinese PSUs, so steer clear. If you're going to power your PC that costs above 50,000tk with a cheap 500tk PSU, don't blame the manufacturers. It's you who's being a Taylor Swift.