Dell S2440L Monitor Problem...

Hai everyone,,

I just buy a Dell S2440L monitor and im pretty happy with picture quality....

Many says text isn't clear etcc... but i've a good pretty monitor with clear text which can adjust in settings....

but, when any light r fan r any other electrical components switched ON then monitor gets off for a while (about 2 sec) and again sets right again...

I've observed dis happens only while using HDMI .No problems with VGA connectivity..
but i want HDMI as i've  Nvidia GTX 650Ti for gaming purpose....

Plz.. Help me...