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PCB Design and Features

The new card is externally identical to the Sapphire Radeon HD 7870 OC. It can only be identified by the FleX stickers on the fans of the Dual-X cooler.


Otherwise, the two graphics card models look exactly alike.

The Sapphire Radeon FleX HD 7870 GHz Edition measures 254x105x40 millimeters.

Its key difference from the Sapphire Radeon HD 7870 OC is about the connectors. It is equipped with one dual-link DVI-I, one dual-link DVI-D, one HDMI 1.4a and one DisplayPort connector. There’s also a vent grid in the card’s mounting bracket to exhaust the hot air from the cooler.

It is this nonstandard selection of interfaces that constitutes the key feature of the Radeon FleX HD 7870 GHz Edition. With these connectors and the included adapter the graphics card can be linked to three inexpensive monitors with DVI outputs. And a fourth monitor can be connected via DisplayPort. Monitors with DisplayPort and HDMI inputs are known to be rather expensive, so the Sapphire Radeon FleX HD 7870 GHz Edition can help you save some money. Sapphire even positions this card as a gaming solution, but we already know that multi-monitor setups and high display resolutions call for a very fast graphics subsystem. We’ll discuss this issue in more detail in the next section.

Two 6-pin power connectors and one MIO connector for building 2-way CrossFireX configurations can be found in their conventional places on the PCB.


Interestingly, the PCB follows an original rather than the reference design.


The GPU-related power section is located not between the video connectors and the GPU chip, as on the reference Radeon HD 7870, but at the back of the PCB. It incorporates as many as six phases.


There are two more phases for memory and PLL which are located in the front part of the PCB along with an Analogix ANX9830C converter that translates DisplayPort into HDMI signals. There’s also a voltage controller NCP4206 on the PCB.


We wonder if it is the original selection of video interfaces that required a redesigned PCB or Sapphire engineers just felt like experimenting.

Another special feature of the Sapphire Radeon FleX HD 7870 GHz Edition is that it has two BIOS chips and a switch to choose the one to use.

Reference Radeon HD 7870s lack this feature, of course.

Our sample of the card has a rather new 28nm Pitcairn XT. It was manufactured in Taiwan on the 17th week of 2012 (late April).

It has a standard HD 7870 configuration with 1280 unified shader processors, 80 texture-mapping units and 32 raster back-ends. The first BIOS chips contains the standard GPU clock rate of 1000 MHz whereas the second one, 1050 MHz (+5%). The GPU clock rate is dropped to 300 MHz in 2D mode.

As opposed to the Sapphire Radeon HD 7870 OC which is equipped with memory chips from Hynix Semiconductor, the Sapphire Radeon FleX HD 7870 GHz Edition carries eight FCBGA-packaged chips of GDDR5 memory from Elpida for a total of 2 gigabytes.

Labeled EDW2032BBBG 50-F, these chips are rated for 5000 MHz. They are clocked at 4800 and 5000 MHz by the standard and overclocked BIOS, respectively, so we don’t expect them to be any good at further overclocking. The memory frequency in 2D applications is 600 MHz. The memory bus is 256 bits on Radeon HD 7870 and HD 7850 cards.

So, here is a summary of the Sapphire Radeon FleX HD 7870 GHz Edition specs with its two BIOS versions.



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