AMD Radeon HD 6990

AMD Radeon HD 6990
$712 ❘ AMD
Add to Cart












Specs: GPU: Dual Cayman XTs; Core clock: 830MHz; Memory: 256-bit bus, 4GB
GDDR5 (1,250MHz); 3,072 stream processors; 192 texture units; 64 ROPs
Test system specs: CPU: 3.33GHz Intel Core i7-980X; Motherboard:
Gigabyte G1.Sniper (Intel X58); RAM: 4GB OCZ DDR3-2000; Storage: 256GB
Plextor PX-256M2S-02 SSD

I t’s no exaggeration to say that AMD’s latest
dual-GPU monster, the Radeon HD 6990,
is the fastest graphics card on the planet, but
context is crucial to evaluating what AMD
accomplished with this card.
The former king of the hill, AMD’s
dual-GPU HD 5970, features two 40nm
Cypress GPUs down-clocked to keep the
card below the 375-watt PCI-E spec. The
6990, also sporting a pair of 40nm GPUs,
has double the memory (on the same 256-bit
bus) and an additional 32 texture units.
Between Cypress and Cayman, AMD
also tweaked the graphics architecture,
split the graphics engine in two for
better vertex and geometry performance,
and moved from VLIW5 (Very Long
Instruction Word) to VLIW4-based
design that significantly optimized the
parts of the GPU that worked the hardest.
The revamped SIMDs are capable of
delivering better compute performance
in less space. AMD provided the 6990
with the 6950’s 830MHz core clocks, and
the 4GB (2GB per GPU) of GDDR5
memory is clocked at 1,250MHz. And
then there’s the second BIOS.
Like the 6970 before it, the 6990
features the same dual-BIOS toggle
switch, questionably dubbed “AUSUM”
(Antilles Unlocking Switch for Uber
Mode) which lets you run an overclocked
profile at the flip of a switch. When set
to the No. 1 position, the Radeon HD
6990 jacks its core clock up to 880MHz
and raises the core voltage from 1.12V
to 1.175V. At the overclocked settings,
the 6990 goes from a 375-watt beast to
a 450-watt monstrosity. To cope, your
system will need to have two 8-pin PCI-E
power connectors; AMD recommends at
least a 750W PSU to power one 6990.

AMD redesigned the PCB, separated
the GPUs with a large central fan, used
separate vapor chambers, and stuck
them to the die surfaces with a special
phase-change thermal
interface material. AMD
also used a pair of digital
Volterra regulators to
manage power fed to

the GPUs and binned
chips for low leakage and
superior OC headroom.
The backplane features
a single DL-DVI port and
four mini DisplayPorts,
letting you set up a fivedisplay
Eyefinity array.
AMD includes three
miniDP adapters (two
DVI and one HDMI) to
get any three monitors
running in Eyefinity right
out of the box.
At $699, the Radeon
HD 6990 is soul-crushingly
expensive; however, take
a look at the numbers
this card posts. To really
appreciate it, you need to be
running multiple monitors,
and that ain’t cheap either.
This single package is
the best-performing card

around, and it’s priced
as such because the
equivalent CrossFireX
configuration with
a pair of 6970s will
set you back roughly
$640 (after rebates).
Oh, and the single-card
performance crown?
AMD still has it.

Specs & Scores        HD 6870    HD 6990   HD 6990 OC
Core Clock            900MHz     830MHz    880MHz
Memory Clock          1,050MHz   1,250MHz  1,250MHz
Memory Interface      256-bit    256-bit   256-bit
Memory                1GB GDDR5  2GB GDDR5 2GB GDDR5
3DMark 11
3DMark Overall        P4263      X3289     X3429
Graphics Score        3935       3045      3183
Physics Score         7937       8061      8051
Combined Score        3991       3461      3595
Graphics Test 1       18.92      14.39     15.02
Graphics Test 2       19.23      17.61     18.51
Graphics Test 3       23.96      15.4      15.97
Graphics Test 4       11.47      9.02      9.45
Physics Test          25.2       25.59     25.56
Combined Test         18.56      16.1      16.72
Unigine Heaven
FPS                   17.6       50.3      52.5
Score                 444        1266      1322
Games 1,920 x 1,200
Left 4 Dead 2         95.21      170.64    172.61
S.T.A.L.K.E.R.:       24.03      63.5      66.2
Aliens vs. Predator   25.7       77.3      80.1
Games 2,560 x 1,600
Left 4 Dead           264.65     140.5     145.61
S.T.A.L.K.E.R.:       14.1       40.5      42.4
Aliens vs. Predator   15.8       48.4      50.7

Article From Computer Power User  Magazine