I knew it was a gamble but we purchased 5 of them and only 3 worked.  One came on enough for me to get it set up but then after turning it on and off a couple of times, now it won't turn on at all.  The second one works but the computer loses signal with the screen several times a minute and blinks.  I have tried new cables and different monitors.  It doesn't not matter.  So they were cheaper but I only got 3 to work.