Since there were no posts for a month (until the previous comment), I'm guessing the OP figured out the problem.
However, the simplest solution (new stuff brought in at the same time the problem started) is likely the simplest answer (and the best place to start troubleshooting).
If all of the new equipment was plugged into a UPS, then unplugging the UPS would b the simplest test to start with. If you know when the problem is happening (same time, etc), run the test then. If you don't, then you'd need to unplug the UPS, and probably shut it's loads down if you'll need to leave it unplugged longer than the unit's runtime on battery.
Another few things to try (again, if the problem has been resolved, this is just for the benefit of others who might have similar problems):
- Put the UPS on a filter (as suggested by several others here).
- Move the UPS to a different outlet on the other phase (using a long extension cord - rated for the load of the UPS).
- Plug the UPS in through an *even longer* extension cord - as wire length reduces the level of the noise in many cases.
If doing those things stops the issue, then it points back to the UPS being the problem, and a filter is probably easiest solution. If removing the UPS from the picture doesn't solve the problem, then it could be one of the other LED lights mentioned - or a combination of them and the UPS - and additional circuit-by-circuit troubleshooting would be needed. The hardest part is chasing an intermittent problem. Because if you can't reliably reproduce it, it's hard to be sure it's gone.
