You're going to get ribbed for not putting this in Cases & Cooling, but anyway...
Of course one's temperatures depend on many factors: The core type, the kind of case you have, the cooling solution you have implemented (or lack thereof), the room temperature, where the case is located within your room, the list goes on...
There simply is no standard temperature, but a range that is satisfactory. I find people are paranoid about CPU temperatures in general.
53 degrees sounds acceptable, but we need to know more about your set up to draw a conclusion. I'm fairly certain your CPU can handle temperatures up to 90 degrees, but I would worry in the sixties and seventies. It's not hard to keep an AMD CPU cool. Mine runs at between 36 and 48 degrees depending on the situation and the room temperature.