Nothing wrong with the Antec, except for it being louder than I would like.
OK, in that case its worth trying to do something about the fan rather than getting a whole new PSU.
I could do a fan swap, but the I don't know what kind of airflow range I should look at.
I suspect the fan is due to smaller heat sinks used to save on cost and I wouldn't want to risk it unless I knew it would be enough.
Consider this: You have a 450W PSU. You are using 150W max. Therefore the PSU is only wasting around a third of the maximum heat that it is intended to dissipate. You would therefore need the fan to be spinning at only a third of the maximum speed to clear the heat effectively. What I would suggest you do is 5V the PSU fan. This will bring it down to a near-silent level and should keep the PSU more than cool enough at this power range - all you lose is some of the crazy amount of power reserve that you have as it would then be unwise to expect it to put out 400W plus.
To 5V the PSU fan you can do this internally within the PSU with a soldering iron onto a 5V terminal or you could use a 5V adaptor on an external molex.