The question immediately arises as to what is different between the Z68 and Z77 chipsets. The big thing does not matter to me, namely that the Z77 supports pciE rev 3.0 - this might be very important to someone planning to install very high end graphics cards. Also the Z77 came along about the same time as Ivy Bridge CPU's. All this means is that a Z77 board is likely to have support in the BIOS for Ivy Bridge processors right out of the box, whereas a Z68 board might require a BIOS update.
The Z77 chipset supports USB 3.0 "natively", i.e. in the chipset itself. What this probably means is that a Z77 board will offer more USB 3.0 capable ports. For example, in the boards being discussed, the Z68 board offers a total of 16 USB ports: 12 USB 2.0 ports supported by the chipset, along with 4 USB 3.0 ports implemented via ASMedia chips. The Gigabyte Z77 board offers 14 USB ports, but 10 are USB3 and 4 are USB2.
All of these boards have the Intel 82579 gigabit LAN chip, which is very nice, my first choice.
Something to watch for if you have a PS/2 keyboard you like very much, is whether the board has a PS/2 connector. A lot of boards these days are dropping this, but it seems that gamers (and discerning programmers) prefer the PS/2 keyboards. The Z68 board does not have a PS/2 connector, the others do.
The Gigabyte no longer has a good old COM port (so I have to get a USB to serial gadget to do some things). The Z68 board also lacks one, but the Asus P8Z77 has one - amazingly enough.
This is a premium priced board, with some gaming oriented features that I will never use (for example, it could hold four pciE video cards, two of which are x16 gen3 slots. I am unlikely to even put one card in it, as I find the Intel HD 4000 on chip graphics entirely suited to my needs.
The first two SATA ports are 6G/s (which tricked me for a while when I connected a 6G/s drive to the third port and was upset that it was only set up for 3G/s. Once I connected the drive to one of the first two ports, it was recognized as a 6G/s device. Some people get wound up that a hard drive cannot generate sustained 6G/s rates, which is silly. When I pull one sector off the drive or something out of the on drive cache, I want it to move at 6G/s, even if it is only one sector.
Note that SATA-3 (aka SATA-iii) requires special cables, and this is not just silly labelling. The cables use twinaxial wire inside and are necessary for the 6G/s data rates.
All told there are 10 SATA interfaces. The first 6 are handled by the Z77 chipset. The first two of these are 6G/s, the other 4 are 3G/s. The other 4 interfaces are handled by the Marvell chip, which I have been cautioned to avoid - it is there for people who think that BIOS raid is their cup of tea. The Marvell interfaces are rated at 6G/s -- and I will try them in the unlikely event that I fill up the chipset interfaces. Also note that the last of the 6 chipset SATA interfaces gets disabled if a SSD is plugged into the mSATA port on board.
This board has a well regarded Creative Audio sound setup based on the CA0132 chip. It worked immediately under linux and sounds fine, so I have no complaints.
There are two network interfaces. One is an Intel gigabit interface, which pleases me and worked immediately. The second is a comprehensively useless Atheros "killer" E2201 interface. All I can say is I sure am glad the Intel network is on there or this board would have been returned.
This board has 14 usb connectors. There are 6 on the back panel, all of which are USB 3. There are 8 available via internal headers. 4 of these are USB 3, the other 4 are usb 2.
The internal headers are different and easy to distinguish. The USB2 headers have 9 pins, the USB3 headers have 19 pins. This means that with the case I have, I cannot connect the cable from the front panel USB connectors to USB 3 headers. However, Gigabyte supplies a front panel bracket (that would go where a floppy might have gone in the dark past). This bracket and cable solves the problem of bringing USB3 out to the front of the case.
The Gigabyte board comes with a wireless network daughterboard and a couple of antennas. So far I am not using this, but I would like to set it up as a wireless hotspot if it is possible to do that. It is an Atheros products, so it remains to be seen if the linux Atheros driver situation makes this useless also.
It has 16 usb ports, of which 6 are USB 3 and 10 are USB 2. The Z77 chip provides 14 of the ports, 4 of which are USB3 and 10 are USB 2. An extra pair of USB 3 ports are provided by an ASmedia chip. Six USB ports are on the back panel. Four of these are USB3 (indicated by a blue color). Two of these are from the Z77, and two are from the ASmedia chip. There are 10 USB ports available via internal headers. One of these headers is the special 19 pin that provides the pair of USB3 ports to the front panel (which my case cannot use). The other 8 ports are available via four 9-pin headers. Unlike Gigabyte, Asus does not give you a front panel USB3 bracket.
This board has 8 SATA connectors. No eSATA (unlike the Gigabyte). Four of these are 6 G/s and four are 3 G/s. Two of the 6G/s ports are provided by the Z77 chipset and the other two are provided by an ASmedia chip. All of the 3 G/s ports are provided by the Z77.
I feel better about the ASmedia chip than the Marvell chip that everybody seems to use, but maybe I shouldn't.
Here is the layout, as viewed from the back of the board with it sitting on a desktop: Z77-3 Z77-3 Z77-6 AS-6 Z77-3 Z77-3 Z77-6 AS-6 The numbering as given by the current linux kernel is: 5 3 1 7 6 4 2 8 In other words the linux kernel runs through the Z77 ports first, beginning with the 6G/s pair, then tacks the ASmedia chip ports on at the end. Fine as long as you know what is up.
This has two SATA 6 G/s and four SATA 3 G/s interfaces supported by the Z68 chipset, along with two 6 G/s interfaces on a Marvell chip.
The "Gen3" in the model number seems analogous to the "3" in the Gigabyte board in touting that it supports pciE gen3, which is immaterial to me, but might get gaming people excited.