Hey guys i'm putting together an a-la-cart PC for Sonar X3 and beyond, and i have found a Gigabyte GA-Z270X-UD5 Motherboard, with Intel Z170 Express Chipset, and would like to know if these boards are good, have problems, or if there's a better choice. TIA.
Looking forward to no more crashes and latency issues.

Motherboards are not as important as they used to be, as a performance part of a PC, and generally, it's better to get away with as little as you can, and invest the money in the processor, ssd, graphic card and so forth.
 
The Gigabyte GA-Z270X-UD5 seems a very good choice for the following reasons:
- it's one of the very few boards with integrated Thunderbolt 3
- NVMe PCIe Gen3 x4 M.2 Connector, which will enable you to use the best NVMe SSD to their full potential (in my old computer, I had to purchase a PCIe to M.2 adapter card, since the native M2 port only supported 2 lanes = half the speed of top notch ssd)
Highly recommended: Samsung 950 Pro M.2 or newer. After numerous Windows/Bios configurations, my PC starts in 3-4 seconds.
- USB 3.1 type C ports
 
Tip 1: make sure it is compatible with your processor
Tip 2: if your processor is very recent, you may have to update the bios before the motherboard recognize the processor. Generally, it's very easy, just plug a USB stick with the new firmware on the designated usb port. On modern motherboards, you can flash the bios with no processor installed. 

That is a "Z270" chipset board and NOT a Z170.  
 
 

Motherboard choice is important for a top-performing DAW.
A quality motherboard will expose all parameters to maximize CPU performance, minimize DPC Latency, and offer detailed control over fan speed.

Do you have any proof of this on a reasonably modern platform ?
 
All benchmarks I've seen is that modern comparable mb - I'm not speaking of cheapos, but mb from asus, gigabyte, msi, ...) are generally within a percentage point of performance of each other, and more often than not, the much higher priced ones have lower perfs. The price difference between mbs can be astounding and amount to a few hundred dollars difference.
 
Granted, these are general benchmarks, not specifically for DAWs performance.
 
Even in the case of better perf, one would still have to check if the price difference is not better invested in CPU, SSD or other key component. Again, I have no DAW-specific benchmarks, and would love to see some, but it's absolutely true for general purpose computing.

I wouldn't question Jim on what he posts.  He builds DAW PC's for a living and has done the "leg work" investigating the hardware.

Jim Roseberry
Motherboard choice is important for a top-performing DAW.
A quality motherboard will expose all parameters to maximize CPU performance, minimize DPC Latency, and offer detailed control over fan speed.

Jim:  I am about to upgrade my system. What mb, cpu, memory, hds, graphics, power supply would you suggest for good performance with Sonar Platinum. I do some basic recording of guitars & vocals, mixing of between 40-60 tracks with a moderate use of plug-ins, and some mastering. Along with SP I use iZotope Ozone 7 Advanced, AD2, Waves, Softube, and some freebie plug-ins.  I don't really do a lot (currently) with midi instruments. I want something that would be upgradeable for the near (3-4 years) future and need to also purchase a new interface (a 2in/4out with at least one headphone (prefer 2) out(s). Been looking at the Audient iD22.  Sorry if this is asking too much for you to bother with, but would appreciate any tips you may suggest. Peace.

CedricM
Do you have any proof of this on a reasonably modern platform ?

Aren't you the same guy who asked for proof that Microsoft doesn't support "PCIe via Thunderbolt" for Thunderbolt-2 controllers?   
 
There are certain BIOS parameters that affect DPC Latency.
Some motherboards expose these... others don't.
If you don't have access to them, you have no means to tweak them.
 
This has nothing to do with generic Passmark benchmark tests.
While those tests reveal important aspects of performance, they do not tell the full story for working with low latency audio.
 
Some motherboards provide more detailed control over CPU throttling.
Some motherboards provide more detailed control over fan speed.

Jim: That wasn't me. But thanks for the reply.