I have nothing but all factory Defaults and a simple cube....(Typical Start-up with a changed theme.)
1 Month ago, I installed Blender 2.78c as an upgrade from 2.77. I had this issue then too. I was able to use GPU for renders until I installed 2.78c before. Somehow I found a forum that had a working fix. It worked! :D but then later, I installed Blender 2.79 and lost the OpenCL option in the user pref. but I was still able to select it in the properties window under render even though it was grayed out.
It seemed to work okay, slower than before but faster still than CPU. Then I installed Sensei Format and then everything went to crap. CPU Render times Shot through the roof and my computer slowed way down just to use Sensei. I uninstalled Sensei and everything went back to normal except now with 2.79 I lost the ability to choose GPU compute under render in the properties panel and still didn't have the OpenCL option in user pref.
So today I uninstalled Blender completely and wiped the computer of anything blender. Updated my graphics driver (Which needed to anyway)then reinstalled Blender 2.79. No good Nothing worked. Only CPU and it took 7.5 hours to render 35% of a scene containing a cube with a glass shader, a UV Sphere with a glossy shader and a basic sky texture. No way that should have taken that long with 8gb of RAM and a duo-core proc. So I did another complete blender wipe and reinstalled Blender 2.78c. That same scene rendered in 3.5 min. with CPU. So obviously this reinstall was good. Better CPU render time and I had the option for the OpenCL back in the user pref. However, when I select GPU (It is no longer grayed out) it gets stuck on loading the kernels and stays at 0% for 30 min before finally it crashes the computer. This is where my problems lay.
UPDATE: I have discovered that the reason Blender wont render on GPU is because when it starts, the Loading of Kernels drives my Physical Memory into the ground. Is there a way to fix that?
Graphics Card Specs:
Card name: AMD Radeon HD 7480D
Manufacturer: Advanced Micro Devices, Inc.
Chip type: AMD Radeon Graphics Processor (0x9993)
DAC type: Internal DAC(400MHz)
Device Key: Enum\PCI\VEN_1002&DEV_9993&SUBSYS_1850103C&REV_00
Display Memory: 4039 MB
Dedicated Memory: 480 MB
Shared Memory: 3559 MB
Current Mode: 1920 x 1080 (32 bit) (60Hz)
Monitor Name: Dell E2416H(Analog)
Monitor Model: DELL E2416H
Monitor Id: DELA0C9
Native Mode: 1920 x 1080(p) (60.000Hz)
Output Type: HD15
Driver Name:
aticfx64.dll,aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
Driver File Version: 8.17.0010.1404 (English)
Driver Version: 15.201.2401.1001
DDI Version: 11
Driver Model: WDDM 1.1
Driver Attributes: Final Retail
Driver Date/Size: 2/17/2016 10:36:30, 1469808 bytes
WHQL Logo'd: Yes
WHQL Date Stamp:
Device Identifier: {D7B71EE2-DAD3-11CF-F076-5A38BEC2C535}
Vendor ID: 0x1002
Device ID: 0x9993
SubSys ID: 0x1850103C
Revision ID: 0x0000
Driver Strong Name:
oem48.inf:ATI.Mfg.NTamd64.6.1:ati2mtag_Trinity_Desktop:15.201.2401.1001:pci\ven_1002&dev_9993&subsys_1850103c
Rank Of Driver: 00E60001
Video Accel: ModeMPEG2_A ModeMPEG2_C
Deinterlace Caps:
{6E8329FF-B642-418B-BCF0-BCB6591E255F}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,1) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_BOBVerticalStretch
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{6E8329FF-B642-418B-BCF0-BCB6591E255F}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,1) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_BOBVerticalStretch
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(YV12,0x32315659) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{3C5323C1-6FB7-44F5-9081-056BF2EE449D}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,2) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{552C0DAD-CCBC-420B-83C8-74943CF9F1A6}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,2) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{6E8329FF-B642-418B-BCF0-BCB6591E255F}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,1) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_BOBVerticalStretch
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(NV12,0x3231564e) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC1,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC2,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC3,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(IMC4,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(S340,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(S342,UNKNOWN) Frames(Prev/Fwd/Back)=(0,0,0) Caps=
D3D9 Overlay: Not Supported
DXVA-HD: Not Supported
DDraw Status: Enabled
D3D Status: Enabled
AGP Status: Enabled
Computer Specs:
Windows 7 Professional 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_ldr.170512-0600)
Language: English (Regional Setting: English)
System Manufacturer: Hewlett-Packard
System Model: HP Compaq Pro 6305 SFF
BIOS: Default System BIOS
Processor: AMD A4-5300B APU with Radeon(tm) HD Graphics (2 CPUs), ~3.4GHz
Memory: 8192MB RAM
Available OS Memory: 7630MB RAM
Page File: 3577MB used, 11681MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7601.17514 32bit Unicode
I am using Blender 2.78c (Downgraded From 2.79 with Sensei Format). Sorry for all the information.