Club 3D unleashes its triple-slot,
dual GPU monster
Although rumours have been circulating for
some time now about an official release of the AMD Radeon HD 7990 6GB, the card
itself has yet to surface, and it now seems unlikely that it ever will. That
hasn't stopped Club 3D from stepping up to the mark, however, and releasing it
gigantic version featuring two fully powered Radeon HD 7970 3GB GPUs on a
single PCB. At $1124, it's a lot of money, but it's at least $112 cheaper than
Nvidia's equivalent, the GTX 690 4GB.
Club
3D Radeon HD 7990 6GB
The two GPUs are connected via an on-board
CrossFire bridge, and each one consists of the standard HD 7970 set of 2,048
stream processors, 128 texture units and 32 ROPs. By default, they're clocked
at 900MHz, but a small red button on the rear I/O switches the card between its
two BIOS modes and overclocks the GPUs to 925MHz, the stock frequency of a
regular HD 7970 3GB. If it actually implemented a worthwhile overclock, it'd be
a nifty feature, but as it is, it's rather gimmicky.
Each GPU also features six 64-bit memory
controllers connected to 3GB of GDDR5 memory, for a whopping 6GB of total video
memory. The memory is clocked at the reference HD 7970 frequency of 1.375GHz
(5.5GHz effective). Completing the PCB is the power circuitry, which comprises
six VRMs per GPU and four for the memory, which gives the HD 7990 6GB 16+1
phase power. This isn't surprising given that you'll need three eight-pin PCIe
power connections and a minimum 850W power supply just to run it.
An extendable rod is supplied to support
the card, as the massive triple slot cooler takes its weight to 1.8kg and its
length to 312mm. The cooler features two copper baseplates and a massive stack
of aluminium fins cooled by two 92mm fans and an 80mm fan, which exhaust most,
but not all, of their air through the rear I/O panel of the card. Heatsinks on
the PCB provide some cooling for the VRMs and CrossFire bridge and a metal
plate on the rear of the PCB does the same for the 12 memory chips found there.
A dual-link DVI, single-link DVI, two mini DisplayPorts
and an HDMI port complete the roster of outputs on the rear I/O panel.
Six-screen Eyefinity support comes as standard, and a CrossFire connection
means that you can even run two of these beasts together in quad-CrossFireX
mode.
The performance of the card varies greatly
depending on the game and resolution used. In every resolution in Battlefield
3, for example, the card scales phenomenally to almost exactly double the
performance of a single HD 7970 3GB, even outpacing the costlier GTX 690 4GB.
However, other games like Crysis 2 and The Witcher 2 tend to only scale
effectively across multiple screens. In single resolutions, the card is limited
by drivers or CPU performance and thus barely outperforms the single card, and
the GTX 690 4GB comes out on top in most cases with more consistent
performance.
Thankfully, the card has a significant
amount of overclocking headroom, just like the original HD 7970 3GB. I was able
to bump its core clock speed up to 1125Mhz and its memory clock to 1.575GHz
(6.3GHz effective). At this setting, the card comes just short of consistent
silky smooth 60fps in Battlefield 3 across three screens, which is eye candy at
its finest.
As you might expect with those three
eight-pin power connectors, the power consumption of the card is outrageous -
that minimum 850W PSU recommendation is certainly worth heeding. Temperatures
are very respectable for a dual GPU card and a good degree lower than those of
the GTX 690. Finally, the noise coming from the fans only ever starts to
approach annoying levels when the card is heavily overclocked.
The Club 3D HD 7990 6GB is an impressive
feat of engineering, but it's not the best option for high-end gaming, even
though it's generally great across multiple monitors. The somewhat erratic
performance and heavy reliance on drivers is a problem with all multi-GPU
setups, but it seems to be much more apparent in this case than with the GTX
690. The latter card may cost more, but outperforms the HD 7990 most of the
time. Also, two separate HD 7970 3GB cards can be had for little over $963 now,
meaning the $1124 price of this card feels very inflated.
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Details
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Price: Approx $1124
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Manufacturer: Club 3D
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Website: www.club-3d.com
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Required spec: Free PCIe slot, three eight-pin
PCIe power connectors, 850W PSU minimum
Ratings
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Quality: 8
·
Value: 5
·
Overall: 7
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