Ok, so I got a choice between those 2 PSUs for my new haswell build. I know most people will go like Seasonic is best hands down. Though, I would like to discuss it. I have been looking for differences between the two modules and here is what I found.
1. According to newegg, the Corsair PSU supports Haswell while Seasonic does not. After researching I found that the problem with Seasonic is when the CPU goes to sleep mode. The Seasonic PSU has problems with that. It requires you to disable the option on BIOS.
2. Corsair is modular while Seasonic is not.
3. Corsair cables are longer.
4. After reading all Cons on Newegg I found that the Seasonic modules die within 1-2 years for some people and there are many DoA. On the other hand Corsair has lower number of DoA and none commented that their PSU died.
5. Seasonic efficiency is higher than Corsair by 2-3%.
6. Seasonic is somehow cheaper than Corsair (not by much).
Those are the only choices of PSUs I can get. What do you guys think. Thanks.
More about :seasonic s12ii 520w corsair cx500m 500w factors
Seasonic is much better than Corsair's "Crappy" CX PSU.
C6/C7 states are not so important unless you're going to use sleep mode on your PC, If you want PSU that supports Haswell get XFX TS 550W to be sure, Corsair PSU uses cheap capacitors and has poor filtrating stage than Seasonic.
The new sleep states are mainly for laptops and usually come disabled by default on retail motherboards. I rarely go by shopping sites reviews you never know how competent the reviewer was or what hardware configuration they ran. The CX series starts strong out of the gate its later on that the cheap secondary caps start to degrade and cause problems, which is why even though it has good reviews(professionally done reviews), it not really recommended anymore. For me the Seasonic would be an easy choice over the Corsair. The only Corsairs I would suggest are the AX(i), HX, and TX.