Going green
It's hard to miss the green-coloured heatsinks and PCB.
As mentioned previously, the KHX1600C9D3LK2/4GX represents a 4GB kit of two 2GB modules running at 1,600MHz with timings of 9-9-9-27 and an all-important 1.35V.
The X suffix on the part number indicates that it's an XMP-compatible set, and that means inputting the various latencies and frequency on Intel Core i5 and Core i7 motherboards should be as simple as selecting the XMP parameter in the BIOS.
The kit ships with a recommended US etail price of $158, but is available from Newegg for $136, and its etail listing is on a par with regular modules (1.65V) with the same speed and latency characteristics. UK customers, often at the wrong end of a bargain, will pay around £125 for the same set.
Most decent motherboards will let you reduce the DRAM voltage in the BIOS to at least 1.35V, and a reasonable number have options for 1.25V, too.
Kingston isn't the only company experimenting with low-voltage modules, however, but it is first to market with the combination of high speeds and reduced voltage.