I've got a machine that does it! Two different power supplies. These new PFC 94% go two ways:
with a standard APC modified square wave without current limiting:
1. Powers off instantly when you test the ups - never unplug a ups, you lose ground and a spike will fry your system. You can use a power strip in front of the ups to turn off power without losing ground!
2. destabilizes - The second power supply we had didn't force a current overload (cheap APC don't have current limiting) - the system would corrupt ram and did not have ECC. So basically memtest86 and prime95 would fail instantly and the system would crash shortly on battery .
The cost of double-online conversion was too much, so cyberpower came out with PURE-sine models. They are truly pure sine.
These were too expensive still! so they came out with a super-modified square wave.
Current limiting models will also prevent UPS shutdown.
If you have a server, you can also mitigate the effect by putting each power supply on a separate UPS!
I forgot the electrical term, but there is a huge current rush when it switches and many ups' will just shutdown since they are too cheap to have current limiting. Second the current rush is a problem because it is rejecting the modified square wave, as it rejects more it requests more power and the wave starts to deform as the ups can't keep up, this in turn causes the PFC to want more ! and vicious cycle.
I just got a new dl360e low end special (single 1.8ghz quad core) and I ordered it to not get the super 94$ "blue plug" (has extra pins for communicating via the power cord to the PDU). Anyways i guess they gave me a free upgrade from the regular efficiency "black plug" (no extra wires to access ILO via the pdu). So i'm testing the server out to make sure it doesn't freak out on power outages/self-test.
Not all power supplies are equal here. If i had my choice, i'd rather have the less efficient power supply. The older tricks like running active/passive (99% on ps1 , 1% on ps2) are good enough and quite honestly a DL360 G6 can idle at the same rate as a DL360e Gen8 (G8 means penis in chinese, hence Gen8).
Newer is not always better! Always test your power solution using a loaded server (prime95/memtest) on battery!!