Monitor flicker when UPS power source is changed

[crowbarstrike]

My monitor LG W2043T flickers when UPS changes from AC to batt power and vice versa. My PSU is corsair VS550 and GPU is Gainward GTX 650 ti Boost 2 GB connected by DVI cable

 

[Paperdoc]

I assume you mean that the flicker happens only as the change-over is happening from AC to battery, or the other way. Other than at those times there is no flicker. Right?

For some types of UPS this is normal. The simpler design of UPS simply feeds power from the AC supply on the wall to your computer, plus uses AC from the wall to keep its battery charged. When the AC supply fails, the monitoring circuits in the UPS switch over to converting power from the battery to AC that it can send to the computer. It also must disconnect the link from wall outlet to computer load, so that there are not TWO sources of AC power connected to the computer at the same time. That change of operation takes a second or less, and hence there is a brief time when the supply to the computer (and monitor, or whatever) is unstable. That can cause the brief flicker you see.

On some fancier UPS designs the AC from the wall does only one thing: it charges the battery. At the same time the UPS in it ALWAYS draws power from the battery and converts it to AC to send out to the computer, etc. With this design there is no brief instability during a change of operating mode. However, the power conversion circuits are ALWAYS in use, and the power delivered to your computer is ALWAYS the "synthetic" AC generated by those circuits. This also means that the unit operates with lower efficiency (that is, consumes more power from the wall for the same output power) than the simpler design.

 

[crowbarstrike]

Does this flicker damage anything in my system? like GPU? Thats what i am worried about. My previous GPU was low end and it never made a flicker during change over of power. After installing GTX 650 Ti boost this flickering happens during power change over. This GPU has a power source from PSU.

 

[Paperdoc]

I really doubt this could cause damage. This sort of flicker is caused because for a brief fraction of a second the power supplied to your PSU from the UPS is weaker. That is NOT the same as a power surge with high voltage spikes. The risk of damage is VERY little.