The Antec 180B case thermally isolates the power supply in a separate compartment.  There is a sliding plastic door between the motherboard compartment and the power supply compartment, and the 500W Antec Phantom power supply just barely fits in the case.  First the power supply retaining bracket must be removed from the case, and the power supply's cables must be unbundled.  Both sides of the case must be removed; so far we have been looking at the left side of the case.  The power supply will be inserted into the case from the right side.  This is made more complicated than you might expect because the Antec 180B case has a dedicated 120mm fan about one inch from the power supply to keep it cool.  The power supply's cables tend to rub against the fan unless they are pulled to one side.

 

The retaining bracket must be placed on the power supply prior to sliding it in place.

Next the inter-compartment door must be opened and before the power supply is placed in the case, the power supply cables must be threaded through the opening.  This is only possible when the power supply is located next to the right side of the case, behind the motherboard. 

I recommend that you remove the fan located between the power supply and the lower hard drive bay while you install the power supply. This fan is easy to reinstall, once you realize that it is held in place with two black plastic clips. This photo is out of sequence, because it shows the power supply already in place, however you can see the screwdriver pushing gently against one of the two plastic releases so the fan assembly can be pulled up and out.

The left-hand image shows the cables as they are introduced through the inter-compartment door.  The right-hand image shows the case wiggled into position, with the cables pulled towards you so they do not collide with the 120mm fan.  This forces the cables to make a sharp turn, which can't be good for them.

The power supply is now ready to be screwed into place.

 

Here a picture provided by Antec tech support, which I enlarged to show the tight clearace between the power supply and the fan.

Dust

You can open two doors on the front cover by pushing on them:

After nine months of operation a lot of dust had accumulated: