Design and Specifications

Each of the three cards is unique in its own way but all of them have one thing in common. All of them use nonstandard PCBs and coolers. Let’s take a look at them now.

Sapphire Vapor-X HD 4890 2GB

This model differs from AMD’s reference card in practically everything, from the color of the PCB to the amount of onboard memory and connectors, let alone the unique cooling system called Vapor-X.

The power circuit of the card seems to follow a 4+2 formula where the first and second number are the number of phases the GPU and memory voltage regulators have, respectively. The GPU regulator is based on a 4-phase uP6206 controller from uPI Semiconductor. The memory regulator is based on a uP6201 chip from the same maker.

The graphics card has one 6-pin and one 8-pin connector for power cables.

As opposed to many other versions of ATI Radeon HD 4890, the Sapphire card has 2 gigabytes of onboard memory and some of the GDDR5 chips are placed on the reverse side of the PCB. Thus, there are eight 1Gb chips on each side of the card. They are clocked at 1050 (4200) MHz which is considerably higher than the Radeon HD 4890’s standard 975 (3900) MHz. This factory overclocking ensures a growth of memory bandwidth from 124.8 to 134.4GBps.

The GPU frequency is pre-overclocked to 870MHz, too, but it does not reach the Radeon HD 4890 OC’s 900MHz. The ordinary Radeon HD 4890 has a GPU frequency of 850MHz. The core configuration is standard: 10 execution SIMD cores (160 superscalar processors with 5 ALUs in each), four texture processors (equivalent to 40 TMUs), and 16 raster back-ends.

The Sapphire Vapor-X HD 4890 2GB offers an original set of connectors including DVI-I, HDMI, D-Sub and DisplayPort. There are vent slits in the top of the card’s mounting bracket for the hot air to leave the system case. Besides, the card supports CrossFireX technology and has a couple of appropriate connectors.

The cooling system is the most original part of the Sapphire Vapor-X HD 4890 2GB. Unlike most coolers for top-end graphics cards, it has no heat pipes. This doesn’t mean that the card is cooled by a simple heatsink with split ribs that resembles Intel’s boxed coolers. Instead of heat pipes, this cooler makes use of a vapor chamber. 

Although the vapor chamber does not resemble heat pipes, it works in much the same way: the coolant is evaporated in the hot part of the chamber to be condensed in the cold part. As a heat pipe, the vapor chamber is hermetic and has a vacuum inside. Its interior is filled with a porous material that facilitates the circulation of coolant by means of capillary action. The chamber is made from copper.

Sapphire is actively promoting Vapor-X technology, but we can’t name a definite advantage of it over conventional heat pipes other than the compactness of design. The chamber directs the heat flow to the round heatsink with split ribs which, in its turn, is cooled by an 80mm fan that has unusually shaped blades. Despite the cooler’s casing, some of the hot air remains within the system case.

The voltage regulator’s power transistors are cooled by a small heatsink with Sapphire logo. The memory chips on the reverse side of the PCB are equipped with a dedicated L-shaped heatsink and should not overheat. So, there is nothing extraordinary about this cooling system and we are not prone to blindly believe any marketing announcements. We will check out the efficiency of Vapor-X technology ourselves shortly.