Corsair once more decided to enrich their portfolio with, this time, a PSU series mostly addressing mid-level systems and users with an average budget. The CS650S is only ten bucks cheaper than the RM650 and lacks the fully modular cabling design of the latter; however, it achieved a higher overall efficiency and tighter voltage regulation on the +12V and 5V rails while sporting a slightly quieter operation than the RM650, which is also a very quiet unit, and both PSUs even registered very close overall performance scores. That said, the CS650M could have easily achieved a higher overall performance score to leave the RM650 behind had ripple suppression on +12V only been better.

If you think you can live without the fully modular cables in an attempt to save some money, we suggest you pick the CS650M. Now, if you absolutely hate native cables and don't have a problem spending an additional ten bucks to also get a longer warranty, the RM650 looks like a sweeter deal. Corsair should, in my opinion, lower the price of the CS650M by at least ten dollars if they want to differentiate between the CS-M and RM line more clearly. As it is right now, Corsair probably created some internal competition between their PSU offerings with the introduction of the CS-M line, which is inevitably the downside of having as many PSU lines with very close pricing schemes. Another thing I didn't like in the CS650M was its lack of an MOV in its transient filtering stage, which robs the unit of the means to handle major surges coming from the mains network, so make sure to connect this PSU to a surge suppressor if you want everything to play out safe. I know that doing so would add to the CS650M's overall cost, but I actually connect all of my systems, even if their PSUs utilize MOVs, to integrated surge suppressors or my UPS, and I have never lost a PSU or system to even a major power surge.

To sum up, the CS650M is a good PSU, but I think its price should be lower than 100 bucks to increase its price/performance ratio and widen the price gap between it and the higher RM650 unit a bit. At its current price, many users will definitely consider the longer warranty of the RM650 unit and that unit's similar performance and fully modular design superior because ten bucks isn't a real deal breaker, and I would also like to see a revision of this unit with better ripple suppression at +12V and an MOV.