g3258 r9 270 cx430



what do you mean by max voltage on a 12v line explain please. first time pc builder
 
He means that your current PSU may fail to deliver the necessary amperage and voltage at the 12v rail, hence fails to deliver the necessary power your GPU needs to work properly. It will also shorten the life span of your GPU. Get a better quality PSU than that.
 


so if I don't oc it I should be in the safe zone?
 
As far as specs go, the CX430 can run your card fine, and is able to deliver more max amperage than your card requires on +12v rail, which is the most important aspect when trying to figure out whether a PSU can power a GPU or not. On the other hand you will be safer with a better quality psu than this one. But if you can't afford it, then this will probably do.
 


guess i'll go with a gtx 960 since the recommended is 400 w
 
Power recommendation do not mean much, AMD over estimates the power requirement for their cards just to be on the safe side, what matters is the +12v rail amperage, which your current CX430 can deliver with more to spare, but it is up to you really. The GTX 960 is certainly a faster card than the r9 270, so if you can afford it, it is a better choice.