So currently I am in talks with Sapphire (opened up a Support Ticket) since I am unable to change the VDDC (core voltage) offset with any software whatsoever. I have tried MSI Afterburner (and ticked off voltage unlock settings, turning off ULPS, enabling unofficial overclocking, etc), Sapphire TriXX, Gigabyte's OC Guru and Asus GPU Tweak. None of these tools gave me the option to adjust VDDC offset. 

The reason I am currently interested in adjusting voltages is due to the fact that my 290's instability is caused by core clock frequency so I suspect If I were able to adjust VDDC offsets I might be able to obtain stability without sacking core clock frequency. 

So far my ticket without Sapphire did not obtain much progress however, the CSR I am talking to claims that TriXX won't support VDDC offset since my card has an SKU of 21227-00 which meant my card has an AMD PCB and not a Sapphire Reference PCB (though I didn't really see why this meant I couldn't use Trixx unless Sapphire made some big changes on their own 290 PCBs). However he insisted that I should still be able to adjust VDDC offset which throws out my assumption that my 290 was Voltage Locked. I was then instructed to contact their Tech email and request for them to see if there is a BIOS that could correct my issue. Currently I have not received a response, but when I do I will update this post. 

I also made another post regarding the lack of sensors on my 290(x) on GPU-Z at TechPowerUp's forum. Unfortunately no one has responded yet, I will update this post once I get a response/more information.

Update 10/7/2014
So I made posts on TPU, Overclock.net, and Guru3d forums (No Response). Sapphire Tech still hasn't responded, at this point I have given up. I think there is an issue with the IR 3567B on my card as I2C dumps do not seem to reveal any devices. I ran/tested a version of The Stilt's BIOS which have increased voltages and my card was able run at stock 290x speeds at 1000Mhz for the first time, however ended up black screening. I'm not quite sure what he did with the BIOS it could either be that the voltages for my cards are wonky and as a result his voltage settings helped my card achieve greater stability (though still not fully stable) at 1GHZ core clock, or that his modifications to the bios ultimately causes the core not to stress out as much and as a result didn't result in instant black screens. Either way, I have given up on the 290(x) for now, I am satisfied with its performance and may jump back into it when I have more time (but I will likely jump ship back to NVIDIA by then).