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You made the mistake of taking the label for granted because the Kolink 600w psu's are not capable of delivering 600w on their 12v rails. The Core Series 600w has a pathetic 480w on it's 12v rail and a disclaimer not to exceed 500w total power for continuous power while the KL600M has a even more pathetic 450w on it's 12v rail with the same 500w disclaimer. They are just garbage and it's sad that OCUK are still selling them but as their parent company is pushing them and OCUK get's them for peanuts I doubt if anything will change. To be honest with the power draw of your pc I am surprised the damn thing hasn't blown up which looking on the internet happens quite often with these psu's.
While the BeQuiet you linked to is of better quality than the Kolink it still has only 480v across it's dual 12v rails. Your pc has a power hungry cpu and gpu so you should be looking at a quality 650w psu and sadly there is nothing on OCUK around £55 that I would recommend for your pc. I would have recommended the Bitfenix Formula series 650w at £75 but that and the 750w version are both out of stock. If you hunt around a bit you can find the Gold rated and fully modular Riotoro G2 650w for £73 (basically a Seasonic Focus Plus with a different sticker). If the budget is really tight then shopping around you can find the Corsair CP-9020103-UK CX650M for £62 with free delivery. It's only bronze rated but the quality has improved massively over earlier units and Corsair now gives them a 5 year warranty. It has 648w of it's 650w on the 12v rail so would be more than capable of powering your pc.
yes for me I am going for a 750w EVGA gold G1+ next (which is actually made by superflower) and has a 10yr warranty.