An LCD cannot actually flicker in the sense you are thinking a CRT does. Setting the refresh rate to 70Hz may in fact damage the LCD- it's just used for syncing and you may overload it (at max res that is). 60Hz will probably give you the best image quality. The flickering, it seems to me, may very well be caused by a faulty backlight (that's often the culprit....*ahem* especially when UPS manages to drop it several times *ahem*). Call up the manufacturer and ask for a replacement.
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