Regarding Z170 motherboards, I was actually pricing some out myself just to see. I like to do that from time to time. :)
TL;DR the more expensive one has a lot of features you're paying for that you may not need. If you don't need them, then why buy them? Here again, both are great boards. Buy what you need, not just what is expensive.
Here are 2 options - a budget one and an upper-mid-range one. They are very similar in feature set.
I have not read reviews on either one, you should do that before you buy anything. But again, buy what you need and not just whatever is expensive. This should help explain why, I have highlighted the things the expensive one has that the cheaper one doesn't.
I'm assuming you're looking at an i7 CPU like the
6700-K to put in this.
These are both ATX form factor. If you want extra PCIe cards in addition to 2x GPUs then you may need a Full Tower case, in which case you can get a bigger motherboard too if you like. ATX will fit inside Mid Tower cases or Full Tower.
MSI Z170A SLI Plus - $109.99 (on sale, usually $140)
- No onboard graphics (doesn't matter if you will have dedicated GPUs)
- It DOES have an HDMI slot so maybe it does have onboard graphics ??? Confused.
- Supports DDR4 RAM Speeds up to 3600
- Supports M.2 SSD
- 7.1 channel onboard audio (Realtek ALC1150)
- Fewer USB ports (5 total)
- 1x 3.1 Type-C
- 2x 3.1 Type-A
- 2x 2.0
- Supports up to 8 more USB ports (4x 3.1 Type-A, 4x 2.0)
ASUS ROG MAXIMUS VIII HERO ALPHA - $278.99 (on sale)
- Has
onboard graphics (won't be used)
- Has
Turbo Boost 2.0 (not sure if you need it if you overclock your CPU)
- Supports DDR4 RAM Speeds up to 3866
- Supports M.2 SSD (shares bandwidth with PCIEX4_3)
-
8 channel onboard audio (ROG SupremeFX 2015)
- More USB ports (6 total)
- 1x 3.1 Type-C
- 1x 3.1 Type-A
- 2x 3.0
- 2x 2.0
- Supports up to 8 more USB ports (4x 3.0, 4x 2.0)
-
Built-in Wi-Fi (2GHz + 5GHz)
-
Bluetooth V4.1
The orange highlights are things that probably don't matter at all.
Onboard graphics? Who cares, you will have dedicated GPUs.
Turbu Boost? Who cares, you are overclocking higher than the stock turbo boost would ever allow you to go anyway.
The difference in maximum RAM speed is negligible, I don't consider that a real difference.
I also don't really notice the difference between 7.1 surround and 8 channel sound. But who knows, if you're a real audiophile then maybe you know the difference. (But if you're a real audiophile, you probably want a dedicated sound card rather than this onboard shit, so again, probably doesn't make a difference).
RE the on-board USB ports, the ASUS does have a total of 6, compared to 5 on the MSI. However, the MSI has 2x 3.1 slots compared to only 1x on the ASUS, so you could easily plug in an external hub to one of those 3.1s and end up with more overall ports on the MSI. Both boards have extra connectors on the motherboards to connect even more USB ports if you want, so IMO this is like 6 in one, 1/2 dozen in the other.
Built-in WiFi - Here is a significant difference. The expensive one can connect to WiFi. If you don't need that, then who cares. (I have WiFi on my mobo, but I never use it. In fact, I had to disable it, because the computer would sometimes switch to it and fuck up all my networking).
Bluetooth - Here again, significant difference. If you have bluetooth devices that you want to connect, you need bluetooth. Personally I hate bluetooth devices, the input lag is terrible on them, so to me this is a useless feature, but make your own decision.