I don't believe Photoshop is designed to allow the use of OpenCL on a 32 bit system (Chris Cox or someone from Adobe will have to speak to why that is). I have a 64 bit Windows 7 system and the OpenCL checkbox is grayed out in the 32 bit variant; it's only selectable in the 64 bit variant.
Im using AMD A8-4500M APU with Radeon(tm) HD Graphics HD7460 running on windows 8 x64.
I have the same problem. I cant run photoshop extended. No 3D layer Menu and OpenCL Checkbox is DISABLED.
The 3D menu is present if you have an extended serial number.
It would appear, but be grayed out if your system cannot handle 3D (like a bad GPU driver).
Regarding OpenCL on 64 bit Photoshop: Try ATI Catalyst 13.3 beta 3.
Important: As of the time of this writing, no recently released ATI drivers work well with Photoshop. That's why I'm suggesting the beta, which I have been running successfully for several weeks now.
You will not be able to enable OpenCL in the 32 bit Photoshop, as described above.
Additional information :
1. ATI Firepro V4900 with latest catalyst driver work with all advanced options (available)
in photoshop CS6 64bit (no 13.01 update applied yet, would try later)
on Intel CPU with P4000,
* please update to latest Intel drivers even using another GPU for display
2. Nvidia GT430 with latest driver with photoshop CS6 13.01 x64 on AMD Phenom II x6
got similar problem reported "OpenCL not available" from photoshop system information
GT 430 has latest nvidia driver installed, supporting OpenCL for photoshop
double check with GPUz reported problem with an unnecessary
ATI stream SDK driver installed (with CPU drivers).
(currently not using AMD for GPU, this driver is not in use)
once uninstalled ATI stream SDK driver from catalyst install manager,
OpenCL option available in photohsop,
GPUz also did not report error anymore.
This might help to reslove some of the problems with dimmed OpenCL option.