850W Thermalright KG-850-W White ATX 3.1 Gold Modular PSU

Admittedly I haven't actually tested it yet as I haven't got all the parts for a new build. but it's from a reputable and good value brand, 850watts, 80+gold, 5 year warranty and all for £70.
I was looking for a little while for a PSU and this was the best I found for the criteria I had set, arrived on time and with all parts, wrapped and in perfect condition.