I have an old HP Media Center z545 that has been sitting in wait with a dead power supply for a few years. I don't want to get the same 250 watt one because it will just die again. The machine is a good one, good enough for media, gaming, digital sculpting and everyday use. So I want to either find a bigger power supply that will fit the original case without modifications or find a new media center case with lots of vents that is only slightly bigger to accommodate a large enough (reliable) power supply that will not burn up again. The new case needs to fit all of the HP hardware, including the removable drive, front and back usb ports and front card slots and audio/video connections.
I just realized that my computer is the HP z545h Digital Entertainment Center PC, w/PMD (Personal Media Drive Cage). So it has a hook up to a removable drive. I guess I would have to ditch it unless I get the old HP 250W PSU. I can always plug it in via usb.
A TFX form factor PSU will extend one inch deeper into the case than your existing PSU. You would need to check if you actually have the extra one inch of extra space needed to accommodate a TFX PSU. The cooling fan may also end up being obstructed by the case depending on how it is oriented when it's mounted.
The following is from the organization that provides 80 PLUS Certification:
Power supplies are the devices that power computers and servers. They convert AC power from electric utilities into DC power used in most electronics. The 80 PLUS performance specification requires multi-output power supplies in computers and servers to be 80% or greater energy efficient at 20%, 50% and 100% of rated load with a true power factor of 0.9 or greater. This makes an 80 PLUS certified power supply substantially more efficient than typical power supplies.
There are six certifications ranked from worst to best:
80 PLUS Bronze
80 PLUS Silver
80 PLUS Gold
80 PLUS Platinum
80 PLUS Titanium
Consumer PSUs are only currently available with up to 80 PLUS Platinum certification. At this level of conversion efficiency there is very little heat generated due to conversion losses within the PSU. These PSUs are also usually more expensive.