What’s wrong with Asrock Motherboards? (No Display Problem)

I have visited an Internet Café last week because my boss advice me to assist them. While doing some basic troubleshooting I have noticed that there more than 10 computers are dead and some has power but there is no display. I begin checking the power supply, CMOS, display cable,try another working video card and cleaning the RAM of each unit but I have no luck.

I have  tried removing the motherboard in its case to think maybe there is a grounded part and start the unit again but it doesn’t work-no display but has power and everything is working fine. I’m sure it’s not with the monitor because there’s no even a BIOS display.

All of them are Asrock motherboards and had been purchase around 2 to 3 years by their in-house technician. I don’t know if Asrock sucks but my old friends claims it was the best for gaming PC’s and it’s cheaper compared to other brands.

After I have done checking them all, the owner ask my recommendation because he really wants to restored those units in the operation and we ended up planning to replace all those bad motherboards with a new one.  

Note:You guys, be careful when you buy some desktops choose the best motherboards and if you have no idea talk to the expert. Don’t just buy the item because it’s cheap but consider first the quality side or else you're just wasting your money and time.