Using h81m-ds2v and g3258 - Windows 10 will not boot with 2 cores enabled. I along with others first noticed this with build 10162. Updating drivers for motherboard had no effect. Other BIOS settings have no effect. Clean install has no effect. Turn off a core, everything is fine. Enable both cores, boot loop. Many people with different motherboards are having the same problem, links below. ASUS posted they are updating their BIOS due to a microcode update. Is this coming from Gigabyte?
http://forum.asrock.com/forum_posts.asp?TID=441&title=kb3064209-breaks-the-g3258http://answers.microsoft.com/en-us/windows/forum/windows_10-win_upgrade/windows-10-build-1016810240-incompatible-with/01c23c9a-e9a3-4214-b936-270050e25362?auth=1http://answers.microsoft.com/en-us/insider/forum/insider_wintp-insider_install/cant-install-windows-10-build-10162-on-gigabyte/5be9d4ec-fdc4-47bd-9eb6-5b26806cba59OS Name   Microsoft Windows 10 Home
Version   10.0.10240 Build 10240
Other OS Description    Not Available
OS Manufacturer   Microsoft Corporation
System Name   
System Manufacturer   Gigabyte Technology Co., Ltd.
System Model   H81M-DS2V
System Type   x64-based PC
System SKU   To be filled by O.E.M.
Processor   Intel(R) Pentium(R) CPU G3258 @ 3.20GHz, 3200 Mhz, 1 Core(s), 1 Logical Processor(s)
BIOS Version/Date   American Megatrends Inc. F5, 6/19/2014
SMBIOS Version   2.7
Embedded Controller Version   255.255
BIOS Mode   UEFI
BaseBoard Manufacturer   Gigabyte Technology Co., Ltd.
BaseBoard Model   Not Available
BaseBoard Name   Base Board
Platform Role   Desktop
Secure Boot State   Off
PCR7 Configuration   Binding Not Possible
Windows Directory   C:\Windows
System Directory   C:\Windows\system32
Boot Device   \Device\HarddiskVolume2
Locale   United States
Hardware Abstraction Layer   Version = "10.0.10240.16392"
User Name   
Time Zone   Eastern Daylight Time
Installed Physical Memory (RAM)   8.00 GB
Total Physical Memory   7.89 GB
Available Physical Memory   6.04 GB
Total Virtual Memory   9.76 GB
Available Virtual Memory   7.47 GB
Page File Space   1.88 GB
Page File   C:\pagefile.sys
Hyper-V - VM Monitor Mode Extensions   Yes
Hyper-V - Second Level Address Translation Extensions   Yes
Hyper-V - Virtualization Enabled in Firmware   Yes
Hyper-V - Data Execution Protection   Yes
Graphics   ATI Radeon HD 4800 Series
No Peripherals