I've installed 16Gb(4x4) in my computer and everything seems to be running smoothly and recognised by Windows. No BSoD's whatsoever. My question is, why is HWINFO64 reading my memory as "PC3-12800 DDR3 SDRAM SO-DIMM" and each at 800Mhz and Dualchannel memory? Shouldn't it read as 1600Mhz and quadchannel(I might be way wrong here)? The memory productname is KHX1600C9S3/4GX. CPUz reads it like that as well. Should it be this way or is something not quite right?
Firstly, the 2nd gen sandy bridge IMCs are dual channel controllers, not quad channel, so you can't expect 4 sticks to run in a quad configuration: rather the IMC has a dual channel pathway to each pair. Secondly, manufacturers like to hype their memory speed specs, so they often quote DDR in terms of its "bits per second" rate; i.e. PC8500, PC10666, PC12800, PC14900 etc. With 8 bits per clock tick, the frequency (in Hertz) of each of these is 8500/8~1066MHz, 10666/8~1333MHz, 12800/8~1600MHz, and 14900/8~1866MHz, etc. Thirdly, the memory is double data rate (i.e. DDR), and each channel is actually running at 1/2 the stated frequency; i.e. 1600/2=800MHz. But since there two data streams running simultaneously you get the equivalent of one channel at 1600MHz.
I'm impressed you got 4 sticks of 1600 MHz HyperX PnP running at 1600MHz with the G74! There are many threads around here with people who bought 16GB of that stuff or the 1866MHz variety and couldn't get the G74's BIOS to see it as anything but 1333MHz.