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The use of the UVD in the Radeon HD 6800 Series has been deprecated 5 years ago. If this is the GPU used in your i7-2600 system then you would know that hardware encoding quit working for this card back in 2015 when AMD introduced the 15.xx series of drivers which only supported their newer gpu cards with vcn encoders. See this chart: https://en.wikipedia.org/wiki/Unified_Video_Decoder
It might be that the OP is not clear. In the OP not once is anything stated about encoding, just "hardware accel, and openCL", I'm not even sure exactly what that means. If it refers to the pref > Hardware Acceleration and the OpenCL option, that will be available with virtually any card. The value of such option alone may be near zero for one's timeline, but it will be selectable.
But all correct, some old hardware and drivers required to get the very outdated PD15 to use "Hardware video encoder" box on the "Produce" page. But as OP requested, here is a page CL listed for GPU's for PD15,
https://www.cyberlink.com/support/faq-content.do?id=19353
What real features, capability, will be functional with the hardware has never been stated by CL that I've seen for any release.
Jeff