A fully unlocked GeForce GTX 480 with all 512 CUDA cores active, unofficially known as the GeForce GTX 480 Core 512 in some hardware circles, first appeared in the wild in 2010. The card lead to the speculation that Nvidia might bring it to market, but that never happened. Ten years later, another working engineering sample (opens in new tab) of the fabled graphics card (spotted by @KOMACHI_ENSAKA (opens in new tab)) has emerged once again in China.
At one time, the GeForce GTX 480 (opens in new tab) was the fastest graphics card in the world. Sadly, it will always be remembered for the wrong reasons, such as being one of the hottest and most power-hungry graphics cards that ever graced the hardware world, and the unlocked version's high power draw only underlines that assertion.
In case you weren't around then, the GeForce GTX 480 dates back to the Fermi era. The graphics card was based on the enormous GF100 silicon, which TSMC manufactured on the 40nm process node. The GF100 die measures 529 mm² and houses up to 512 CUDA cores. However, the complete GF100 die didn't officially make it to the market. Despite the GeForce GTX 480 being the top dog at that time, it only came with 480 CUDA cores, meaning Nvidia had disabled 32 of them. It was unheard of for a flagship model to not feature the full silicon.
On the outside, the GeForce GTX 480 Core 512 engineering sample utilizes a similar shroud as the GeForce GTX 470 (opens in new tab) with some slight aesthetic changes. The teardown reveals the same PCB design and internal components as the public GeForce GTX 480, though. What's not visible is that the GF100 die that's under the hood does come with all 512 CUDA cores enabled.
Expreview's evaluation (opens in new tab) of the GeForce GTX 480 Core 512 shows a roughly 6% performance uplift over the regular GeForce GTX 480. The puny improvement comes at a very high cost, though. Back in the day, our test system (opens in new tab) consumed up to 450W when we pushed the GeForce GTX 480 to the edge. Expreview's system with the GeForce GTX 480 Core 512 pulled up to 644W under similar workloads, a difference of 194W.
It's easy to see why Nvidia didn't release the GeForce GTX 480 Core 512 when you look at the math. A 6% performance increase at the cost of 43.1% higher power consumption would have only given the Fermi-based graphics card a worse reputation for high power draw.