there are few solution but I can't really know which is the problem...
1. try clean installation of the driver, use driversweeper to uninstall the CCC
2. some overclock model of gpu, like Asus HD 7770 Direct CU II have problem with the overclock and you try to underclock the GPU to the stock clock
3. last option, RMA the card...
When you do uninstall previous versions of Catalyst, be sure to clean-up old files extensively, e.g. by CCleaner.
When you do install Catalyst, it is important that you make a choice for all included driver parts. E.g. at the window were you have a choice to check-mark installing "Fast" or second option for "Adapted" (?? ---> I have no English version). I check for the second option and all included parts within that section.
In past (older versions of Catalyst) I didn't check-mark for "AMD APP SDK runtime" option within that section, as I thought SDK is only for developers. But I met several problems by that. By choosing all the included files, problems where gone.
I don't know if your PSU do have several 12 Volt rails, but be sure not to divide / splitting the 12 volt cable of your PSU for your graphics card to other 12 Volt devices.
Can you trace volt, wattage etc. by using GPU-Z - second tab during a time-span of about 8-10 minutes?
(Under load by using the "render" option of the GPU-Z tool).
Are the found problems the same as from your previous card?
The games, are that more old games, so maybe not fully Windows 8 compatible?
You can try for choosing to run under other compatible modes, by going to the program exe file and by right-click under properties choose for another OS compatible mode (e.g. Windows Vista / Windows 7).
http://www.tomshardware.com/answers/id-1877678/problems-gpu-radeon-7790-1gb.html
Some quick searches see if any apply to your case!