If they are the same price, I would go with the ASUS just because I have had very good experiences with ASUS and don't use Gigabyte boards much.
This is a technical forum. I like the color Red and not Blue, so therefore Red is a better color? You haven't used Gigabyte boards or researched them (and I presume neither on MSI/Asrock) but Asus is the best? OK....
A lot of depth and thought went into this answer, especially since Gigabyte made superior boards in the past.
I prefer the Asus Z170-A board over the Gigabyte board. Good choice.
That tells the OP absolutely nothing about the boards he is considering other than your own bias/preferences.
Let's get on with it then:
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Gigabyte UD3's superior feature set:
1. Superior Audio -
ALC 1150 chip vs. Asus' budget/lower tier ALC892 sound chip. This almost assuredly means that the headphone amplifier on the Z170-A is garbage as well. IMO, if going for an Asus board that even tries to compete with the UD3, the
Z170 Pro GAMING is better than the Z170-A.
2. I/O features - Gigabyte has
2x Ultra M.2 ports,
3x SATA Express ports and 6X SATA 3 ports.
In contrast to that, Asus has a single M.2 port and if it's used, the only SATA Express port the Asus board has is turned off. That means you can only use one or the other on the Asus while Gigabyte. M.2 RAID is also impossible on the Asus board. The Asus board also has just 4x SATA 3 ports.
3. Gigabyte has dual-BIOS chips which means if one of them fails or if you flash your bios and something goes wrong, you can just fail safe boot from a 2nd bios. Asus doesn't have this feature.
4. Gigabyte has 7x USB 3.0 ports vs. 6x on the Asus. Does it matter for the average user? Probably not but it's there.
5. Gigabyte uses 10K Black Capacitors. There is no indication that the Asus Z170-A uses such premium caps. They generally reserve these premium components for their TUF/ROG motherboards, not the mainstream line-up. Gigabyte also uses 15oz Gold in the socket and 2oz copper in the PCB. All of these might not translate directly to more performance on a % basis, but Gigabyte is without a doubt using more premium components on their $149 board. This is also reinforced by Asus skimping on using last generation's 892 audio codec.
Aesthetically, matte black PCB of the Gigabyte looks better than the black/brown PCB on the Z170A.
Asus Z170-A's superior feature set:
1. DisplayPort + HDMI 1.4 + DVI port mean that one could run a triple monitor connection exclusively over digital connection.
2. Asus's UEFI and its advanced fan header controls are class leading.
3. Asus offers an
Advanced RMA program for customers in North America but it has
received mixed reviews. When I had to RMA my Asus P67 board, things went smoothly however.
4. Q-Connector makes it easier to connect the case cables to the Asus board than the Gigabyte's colored scheme on the board.
OP, if you are spending $165 or so on the Z170-A, UD3 is a better board overall. The Asus's better competitor to the UD3 is the Z170 Pro Gaming but Gigabyte's
$169 GIGABYTE GA-Z170X-Gaming 5 board is better than all of these boards.
I personally think Asus makes excellent ROG boards but most of their mainstream boards are overpriced as they skimp on features and use lower end components compared to MSI, Gigabyte and Asrock. The Z170-A looks completely outclassed when the Gigabyte Z170X-Gaming 5 is just $6-7 more. It's downright ridiculous when comparing feature sets and high-end components chosen on the Gigabyte.
OP, read some reviews online for yourself to compare specs/features you need and component choices. Don't just listen to some remember person who has only bought Asus boards for 10 years. Personally, I would never buy a $160 board with an ALC892 codec in 2015 and a board that costs $160 but has only a single M.2 connector/SATA Express port (i.e., why as consumers are we asked to pay so much more for Asus's basic boards, when boards from MSI/Asrock/Gigabyte have such a superior feature set / components at this same price level?). If you really love Asus's UEFI and it's worth it, sure go for it but at least consider the Asus Z170 PRO Gaming then.
thank you im so excited to build my new skylake gaming pc
my old pc is 5 years old and it stutter in some games .
Let us know what your other system components will be such as the GPU choice, monitor resolution, PSU, etc. Also, how long do you intend to keep this system without upgrading the CPU -- 3 years or 5-6 years?
This matters because if you are considering a Core i7 6700K system with a GTX960, it's probably way better to get a Core i5 6600K and a GTX970/R9 390 instead. However, if you intend to upgrade the GPU 2-3 times over the course of 5-6 years while keeping the same platform intact, it could make more sense to spend extra on the CPU at the expense of a weaker GPU. It just depends what your goals and upgrade paths are. Let us know and we can advise you.