Sapphire Radeon HD 7790 2GB OC Reviewccokeman -
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Sapphire HD 7790 2GB OC Closer Look:
Visually different in more than one way than the HD 7790 Dual-X 1GB I looked at a month ago, the HD 7790 2GB OC features a large, single aerofoil dust free fan pushing the air into the shroud in lieu of a pair of fans. Measuring just 8.5 inches from end to end, the card should easily find a home in a small form factor chassis. You will need a motherboard that supports a 16x PCIe slot to use this card. It supports the PCIe 3.0 standard but is backwards compatible to earlier standards. The back side of the PCB is covered with a metal backplate that helps cool the memory ICs on the back side of the custom PCB. You can see the top of the dual heat pipe-equipped cooling solution through the shroud and see that it is configured differently than the Dual-X card.
Display connectivity on the HD 7790 2GB OC includes a single Dual-Link DVI-D, single Dual-Link DVI-I, and one DisplayPort 1.2 that supports MST, stereoscopic 3D and lossless 7.1 channel audio. A single HDMI 1.4a port is included that offers 7.1 High Bitrate Audio and 3D stereoscopic support. Additionally Sapphire has employed its FleX technology playbook on this card so that three monitors can be used without the use of an active adapter. The back end of the card is open to allow airflow from the aerofoil fan to escape the shroud. An interesting addition to the backplate on this card is a fin array that sits in the airstream exiting the card and is used to cool the memory ICs on the back of the PCB.
A single Crossfire bridge connection is seen on the HD 7790 2GB OC showing that Crossfire is supported using up to a two card configuration in motherboards that support AMD's multi GPU solutions. Power supply requirements for the HD 7790 2GB remain the same with a recommendation of a 500 watt minimum needed when a single card is used. Crossfire will require an upgrade to a power supply that is rated at 600 watts. A single 6-pin PCIe power connection is needed to provide the power needs for the card. Sapphire supplies an adapter if the power supply is not equipped with a 6-pin PEG connection.
Pulling apart the HD 7790 2GB OC is pretty straight forward. The heat sink/shroud assembly is held on with four spring loaded screws while the backplate is held on by nine screws. Once apart you can see that much like on the Dual-X-equipped 1GB version, this card comes with a custom PCB. Whereas the 1GB card had a large unused portion of the PCB, the HD 7790 2GB OC uses it to effect with the heat sink attached to the backplate protruding through the PCB and into the air stream from the fan to provide the added cooling to the memory ICs on the back of the PCB. The backplate is metal and serves to not only cool the components under it but to also add structural rigidity with a larger cooling solution to keep the traces in the PCB from cracking.
Sapphire uses a cooling solution that uses a pair of 8mm copper heat pipes to carry the thermal load from the copper contact plate to the aluminum fin array for removal by the airflow provided by the 90mm dust free aerofoil fan. The memory ICs on the front of the PCB are covered by the base of the cooling solution keeping them cool in the process. The heat pipes are soldered to the fin array to promote improved thermal transfer and ultimately thermal efficiency of the cooling solution.
Sapphire has been using fans that feature a dust free design on its non-reference builds for some time now as a way to improve the long term reliability of the solution. A fan that slows down or stops running altogether will cook the GPU in no time and was a leading cause of card failures at one time. This fan is made by FirstD, part number FD9015U12S, and runs on 12V .55a. Nine aerofoil blades are used to push the air through the heat sink and shroud.
AMD and its partners are using a new revision of its popular Graphics Core Next architecture, codenamed Bonaire, on the HD 7790. The Bonaire core is built on a 28nm process with 2.08 billion transistors under the hood. Specifications include 896 stream processors that handle two primitives per clock, 56 texture units, 16 ROPs, and on this version from Sapphire we see 2GB of GDDR5 VRAM still running through a 128-bit bus. A total of eight memory ICs from Hynix, the ever popular H5GQ2H24AFR-R0C, are used that support speeds of up to 1500MHz. Baseline clock speeds from AMD for the HD 7790 are 1GHz on the GPU core and 1500MHz on the GDDR5 memory. Sapphire bumped these clocks up a bit for some added performance using a boost clock of up to 1050MHz on the core and 1600MHz on the memory.
Any way you look at it Sapphire came to the table with an excellent card in the HD 7790 Dual-X featuring a 1GB frame buffer. It listened to the market that wanted a full 2GB on board. Let's see where it makes a difference.