Yamaski, QNIX, and X-Star are all Korean monitor brands, and they are known to deliver monitors with unmatched specs for their price, and there is currently a lot of hype surrounding them on the Internet. For $300 on Ebay (buy on ebay for QNIX/X-Star monitors, everyone does and you get the same quality as on Amazon pretty much) you can get a 1440p monitor for only $300 that is both PLS (Samsung's version of IPS meaning it delivers a significantly better image compared to TN panels and many people prefer PLS to IPS even though IPS is hundreds of dollars more expensive) and overclockable to 120hz (QNIX/X-Star also delivers the only monitors that are both PLS or IPS and 120hz).
It's not that Yamaski isn't a trustable brand as iceclock said, all three of these Korean monitor brands (Yamaski, QNIX, and X-Star) are reputable and known to deliver some relatively reliable monitors with amazing specs for cheap prices. However, Yamaski claim to fame was the Catleap 2B Extreme OC, which at the time was only like $300 IIRC and was both 120hz+ and IPS making it a monitor with unprecedented specs at an unprecedented price. That being said, right now it makes no sense to get Yamaski over QNIX and X-Star's 1440p PLS panels unless you really want IPS 120hz, but like I said, many people actually prefer PLS over IPS and the QNIX/X-Star Monitors are $250 cheaper and are also easily overclockable to 120hz.
Also note that the QNIX QX2710 and the X-Star DP2710 are essentially the exact same monitors, just with different logos. They use the same panel, same stand, etc. The one criticism about the QNIX and X-Star 1440p monitors is that they have crappy stands, but most people don't really care about crappy stands.
See here for further information and o/c help:
http://www.overclock.net/t/1384767/official-the-korean-pls-monitor-club-qnix-x-star