If at all possible, use Win7 or Win8 instead of Win10... check Amazon to see if they still sell either
An idea that MAY work to install and/or run CS6 in Windows 10... works for some, not for others
-RIGHT click the program icon or EXE and select a compatibility mode in the pop up option window
-or Run as Administrator http://forums.adobe.com/thread/969395 to assign FULL Windows permissions may help... says Encore, but sometimes required for ALL Adobe programs (this is NOT the same as using an Administrator account)
-or more on permissions https://forums.adobe.com/thread/2293598
NOTE - Win10 anniversary update version 1607 has caused MAJOR problems with old programs, so the above may not work
the amd ryzen cpu's could help cut costs, or upgrade to an 8 core for the same price, but i don't recall if anyone has had ryzen working with cs6 or had problems. i would put the odds of any ryzen and cs6 compatibility issues as low, and there could just as easily be issues between new/recent intel hardware or new versions of windows as john points out.
intel is about to release a new line of cpu's, which might be slightly better. but if you are worried about cs6 compatibility you might have better luck finding feedback on the web with cs6 and the i7-6800k or broadwell-e cpu's.
as for the radeon duo pro card, i don't think cs6 supports dual video cards. even the current release of premiere and most of adobe's software still have limitations with two video cards, so its better to stick with one.
Windows 7 is NOT a viable option for any newer PCs with newer CPUs. That is because Microsoft now no longer supports anything other than Windows 10 for any PC based on any of the AMD Ryzen or Intel Kaby Lake CPUs. The OP will not receive even security patches, let alone hardware support updates, for Windows 7 if that PC is equipped with any of the newest CPUs or chipsets. Windows 7 will still receive security patches, but the CPU and chipset compatibility will be frozen to pre-Skylake levels.