Summary: Just got this DDR3 dual channel kit in my Z77 system to replace an older set of 1600 9-9-9-24 DDR3 RAM that scored 7.8 on WEI. With the XMP setting in the BIOS, I am getting 1866 10-11-11-30 and a 7.9 WEI score. A modest upgrade, but this is also at 1.5V. Memtest 4.2 found no errors on these at the XMP settings. The heat spreaders are well made and look cool, but do not add much visual bling. This is a nice kit if you can find it on sale.