You probably think that you've already seen all there is to see about AMD Radeon HD 7870 graphics cards, but the Radeon HD 7870 jokerCard 2 GB that Club 3D recently launched is something special indeed. That's because this video card isn't based on the Pitcairn GPU like the other 7870 cards, but instead the Tahiti chip that's traditionally been used for the high-end Radeon HD 7950 and 7970. That makes the 7870 jokerCard faster but not more expensive than the standard HD 7870.
The Pitcairn GPU that's normally the foundation of the Radeon HD 7870 cards has 1280 shader units and a 256 bit memory bus. That GPU is made with 28nm transistors, and has about 2.8 billion of them. The Tahiti GPU in the 7950 and 7970 cards have 2048 shader units and a 384-bit memory bus, and with 4.3 billion transistors this GPU is definitely more powerful.
For its new Radeon HD 7870 jokerCard, Club 3D had AMD create a special version of the high-end Tahiti. AMD called it the Tahiti LE and imposed a few limitations. A quarter of the 2048 shader units were disabled, leaving 1536. That's still a lot more than what Pitcairn has. The memory bus was reduced from 384 bit to 256 bit, identical to Pitcairn.
Clock frequencies also differ compared to the 'normal Radeon HD 7870 cards. The GPU of those cards run at 1 GHz with a memory speed of 1.2 GHz. The Tahiti LE has a GPU running at 925 MHz with a Turbo of 975 MHz, a little slower in other words. The memory speed is much higher, however, at 1.5 GHz. That's the same as the Radeon HD 7970 GHz Edition. Based on those specs you'd expect that this unique Radeon HD 7870 card falls between the standard 7870 and 7950 in terms of performance. The chart below lists the specs side-by-side.