Crashes with new build

Built my new system last week, and I'm having some trouble. System runs great most of the time, but sometimes will redscreen or bluescreen during gaming, movies, or just sitting idle. I suspect the video drivers, since they're beta for Windows 8.1, but not sure.
Parts List:

• Intel i7-4771, cooled by Cooler Master Hyper 212 Evo
• Gigabyte z87x-ud4h
• ASUS R9280X-DC2T-3GD5 Radeon R9 280X
• Samsung EVO 512GB SSD
• OCZ|OCZ700GXSSLI 700W RT PSU reused from previous build
• 16GB GSKILL F3-12800CL7Q-16GBZM
• Windows 8.1
• LG Blu-ray rewriter
• Rosewill Media Card Reader
• Cooler Master HAF X case

So far, I've run Prime95 to test the CPU, which seems to be okay, and ran Memtest x86 for an hour which didn't come up with any errors. I also reinstalled Windows & checked that all drivers are up to date. Temps look okay when checked in BIOS or with HWMonitor. Ran Furmark until GPU temp maxed out at 84C and started cooling down.
It will redscreen pretty reliably in about 2 hours in Tomb Raider or Metro: Last light or CS:GO. I can play Civ 5 all day without a crash, I've also had it red-screen at least 5 times just sitting idle or playing a youtube video.

Attached the debug info / dumps as requested.

EDIT: and speccy snapshot: http://speccy.piriform.com/results/ZoWA4nfgiXOCwaz2OOY50s8

Hi

Please post a "Speccy" snapshot of your system by reading instructions from the below link.

Publish a Snapshot using Speccy - Internet Applications Mini-Guides

It will give us some in depth details of your system configuration.

Speccy Snapshot: http://speccy.piriform.com/results/ZoWA4nfgiXOCwaz2OOY50s8

Sorry for the delayed reply mate.

Stop codes are varying with each crash dumps and there is no patterns can be seen. One of the crash dump is BugCheck 5C HAL_INITIALIZATION_FAILED (5c) which indicates a low level hardware issue/compatibility issue. Please follow the below steps.

1. Reset system BIOS.

How To Clear CMOS (Reset BIOS)

Load default values after resetting. Don't modify voltage, frequency values of either CPU or RAM. Let the system run on optimal default settings.

2. Update BIOS.

There is a recent BIOS update available which improves PCI-Express compatibility. Download and update to it from http://download.gigabyte.us/FileList/BIOS/mb_bios_ga-z87x-ud4h_f7.exe

3. Uninstall Gigabyte utilities.

Please uninstall "Gigabyte" bundled software like "ON/OFF charge" , "USB charger" etc completely from the system. These are problematic in some systems.

4. Update Motherboard drivers.

First uninstall currently installed Intel Ethernet , Marvel SATA , Realtek Audio , Intel Rapid Storage Technology , Intel Management Engine drivers completely from the system.

Download and install "Windows 8.1" specific version of those from the below links.

Intel Chipset : http://download.gigabyte.us/FileList/Driver/mb_driver_chipset_intel_8series.exe

Intel Ethernet : http://download.gigabyte.us/FileList/Driver/mb_driver_lan_intel_8series.exe

Realtek Audio : http://download.gigabyte.us/FileList/Driver/mb_driver_audio_realtek_8series.exe

Intel Rapid Storage : http://download.gigabyte.us/FileList/Driver/mb_driver_intel_irst_8series.exe

Marvell SATA : http://download.gigabyte.us/FileList/Driver/mb_driver_marvell_sata_controller_8series.exe

Intel Management Engine Interface : http://download.gigabyte.us/FileList/Driver/mb_driver_intel_me_8series.exe


If the BSOD continues, please rerun the diagnostic tool and upload the latest crash report with next reply.