Installing the Real Power Pro 1250W was uneventful. It was a little frustrating to have to use a custom power cable. It's not as long as my regular cable, and I had to move my computer closer to the power source as a result.
I really dislike the unit's lack of a hardware power switch. This means that, in order to power off the device, one must physically remove the power cord from the PSU. I expressed my concern for this in the review for the 1000W version, as well as the Zalman 850W a few months ago.
I monitored and benchmarked the unit using OCCT Perestroika on Windows XP Professional 64-bit with an ASUS M3A32-MVP motherboard, Athlon X2 6000+ processor, 8 GB of RAM, two hard drives, a DVD burner, an 8800 GTX video card, and an X-Fi sound card. Spot checks of the 3.3V, 5V, and 12V rails came in at 3.26 V, 5.05 V, and 12.16 V, respectively.
I've included for comparison the results of the OCCT benchmark of the InWin Powerman 1200W I recently reviewed.
The RPP 1250W 3.3V rail undervolted a little, staying between 3.25V and 3.26V. Its ripple was virtually insignificant at 0.31%. The InWin rippled farther, but was more consistently stable throughout the test.
The 5V rail overvolted a little, but overvolting is much more acceptable than undervolting. Again, the RPP's ripple was less, but, on this rail, the RPP was more consistently stable than then InWin.
The 12V on both power supply units was wholly stable. The RPP overvolted by approximately 0.16V, and the InWin undervolted. Both were within reasonable limits.
The PSU is fairly quiet, and certainly no louder than the other RPP series units. I can hardly tell any difference between it and my beloved Antec TruePower Quattro 1000W.