Distorted image could be a result of loose or defective cable connection. Separate video cable from back of PC and confirm that no pins are twisted, broken or burnt. After verifying re-connect monitor cables and check image appearance. If refresh rate isn’t correctly set, then monitor might have wavy lines going down or across monitor at random speeds, that can result into flickering affect. A distorted image could be due to magnetic or other sorts of interference. Thus make certain that no speakers, phone, fans or other magnetic gadgets are close to monitor.