Those brand can modify the gpu thats true but not the basic things....like the driver is meant to be worked for every variant of the card. Like MSI R9 or Asus R9 driver must be worked equally otherwise AMD would make different drivers for different manufacturers
I can't speak to your model if it did, does or ever did support a feature and it does not in the current driver. Feature control however is very much able to be decided by the CARD MAKER NOT AMD. AMD supplies a reference design for the card and their GPU. Included with that is the "Vanilla" driver designed to work with a reference design. The OEM card makers make changes to those board the vary from small to very huge. The vanilla drivers do not account for those changes. This is why the card makers also supply a driver. Their drivers may differ because of those changes. They may also enable or disable features the AMD drives do not.
What is enabled in the driver is not as much dictated by the GPU on the card but by the code in the BIOS of that card. If you are concerned with what your card is or is not supporting the first company you should be speaking to is the company that made your card, not AMD. AMD and it's support community is a great secondary avenue when the OEM's don't do their job supporting their products. Unfortunately though AMD can't fix what they didn't break by an OEM straying from a reference design.
While AMD does not recommend the use of 3rd party tweakers such as MSA Afterburner and Saphire Trixx with Wattman, they are widely used apps by many. Your card does not use Wattman and those utilities may add the functionality you are looking for. So you may wish to look into that.
""Today, we are reviewing the Sapphire R9 290X Tri-X OC, one of the most popular non-reference R9 290X cards on the market. The TriX-OC comes with increased clock speeds of 1040 MHz on the GPU (+40 MHz) and 1300 MHz on its memory (+50 MHz).""
"While the reference cards set the bar for performance and (for better or worse) drive the overall perception of the series, the modern board partner system means that in time we can look forward to partners eventually releasing semi-custom and fully-custom cards, which use custom coolers and custom boards respectively. Customization allows the board partners to differentiate from each other by designing cards around different capabilities – be it size, cooling, or overclocking – in the process creating a wide spectrum of cards for a wide spectrum of use cases. Or with respect to the 290 in particular, customization offers partners a chance to go back and try to improve on the reference 290’s weakness, its noisy cooler."
The first customized 290 series card in our hands, Sapphire’s Radeon R9 290 Tri-X OC is a rather straightforward semi-custom card. Sapphire has taken AMD’s reference design and replaced AMD’s reference blower with their recently introduced Tri-X open air cooler, which as we’ll see significantly changes the cooling/performance equilibrium compared to the reference 290. At the same time Sapphire has also given the 290 Tri-X OC a mild factory overclock to boost its out of the box performance and differentiate it from the reference 290 and competing customized 290s.