Originally Posted by
planet436
Psu's generally degrade by 10% per year and lowish quality psus like Tagans are unlikely to be able to give you 600w brand new anyway. Need to be careful with those sites for 460 wattage, if I remember correctly your model is highly overclocked and with this comes higher power usage over standard 460s.
Your current PSU might be able to handle SLI's but it's going to be close. If you have a friendly store near you they might allow you to borrow a PSU and check if indeed that is the case, or if there is an online store which will allow returns within 30 days if the product is used (not sure about this though).