Enermax Liberty 620W ELT620AWT ATX2.2 Modular SLI Compliant PSU (CA-024-EN)
Price: £87.95 (£103.34 Including VAT at 17.5%)
Brilliant PSU and its modular, the build quality is top notch and all the rails are very stable.
Seasonic S12 600W Silent ATX2.0 Power Supply (CA-002-SS)
Price: £83.95 (£98.64 Including VAT at 17.5%)
Same as above only its not modular but it is virtually silent.
FSP Sparkle FX600-GLN Epsilon 600W ATX2.0 PSU (CA-002-SK)
Price: £76.50 (£89.89 Including VAT at 17.5%)
Again it has the same qualities as both the enermax and seasonic, but its not modular.
Tagan TG600-U25 600W ATX2.0 Dual Engine Silent SLi Compliant Silent PSU (CA-013-TG)
Price: £77.95 (£91.59 Including VAT at 17.5%)
Same again.
Well there you go, i would say you have a choice out of those 4 and which ever one you pick you wont be disappointed.