Compared to Asus Mainboards with the same Chipset
ASUS M2N-MX and M2V-MX etc... Series (not low coast)
with ASRock (little bit cheaper) using same via chipset:
ASROCK ALIVENF6P-VSTA and ALIVENF6G-VSTA etc...
My overall performance with different Graphic boards is by Asrock better. The tuning options in the bios is by asrock ami bioses more extended. I will not say low coast is less good, sometimes it can beat high price brand names.
Did you check your bios setting for the graphic card?