AMD's 790GX core
logic is based on the venerable 780G chipset, but with an overclocked integrated
graphics core and a dedicated 128MB of DDR3-1333 side port memory. In every
real sense, the AMD Radeon HD 3300 integrated graphics is more an integrated videocard than a true IGP which leaches its memory from the system.
While the Radeon HD 3200 GPU integrated into the 780G
chipset ran at a 500MHz core clock speed, the Radeon HD 3300 that's part of
AMD's 790GX chipset has been bumped up to a 700MHz core clock. Other than the
increase in speed, this chip is quite similar to its older sibling - both are
built on the 55nm manufacturing process, have 26 lanes of PCI Express
connectivity, connect to the processor with HyperTransport 3.0, and use AMD's
Unified Video Decoder to offload processing of high-definition H.264, VC1 and
M-PEG2 content from the processor.
The AMD SB750 southbridge is a different story, and has
changed quite a bit from it predecessor the SB700 which was paired with the AMD
780G chipset. This new southbridge now supports RAID 5, in addition to the RAID
0, 1 and 10 functionality.
The SB750 southbridge also makes use of something called
the Advanced Clock Calibration (ACC); this is an interconnect that runs directly
from the southbridge and into the CPU socket. For owners of AMD Phenom and
Phenom Black Edition CPUs, enabling ACC will allow the SB750 southbridge to
tweak the overclocking capabilities of their processors.
Due to the increased graphics capabilities of the
integrated graphics controller, the AMD 790GX chipset supports Crossfire X,
although at reduced bandwidth rates than can be found on non-integrated graphics
motherboards. The AMD 790GX's Crossfire is limited to 8/8 lanes of PCI Express
bandwidth. While this clearly isn't as nice as having a 16/16 Crossfire
configuration, it's still more than enough that even high-end graphics cards
like the Radeon HD 4850 won't become bottle necked.
Naturally, support for Hybrid Crossfire is also
included, which means that the integrated Radeon HD 3300 graphics processor can
be paired with a Radeon HD 3450 videocard, and when running together these two
graphics processors can be about as powerful as a Radeon HD 3650. While this is
a bit of an improvement in overall processing power, it's really not worth
implementing.
|
AMD`s 790GX
integrated graphics northbridge and it's dedicated 128MB of DDR3-1333 memory
(at right).
|
|
AMD SB750
Southbridge core logic.
|
Look at it this way, AMD Radeon HD 3450 videocards cost
around $50, and AMD 790GX-based motherboards can reach as high as $160. That's
more than enough money to get a $100 AMD 780G-based motherboard and a faster
Radeon HD 4670 videocard..... Running Crossfire or SLI on an integrated graphics
chipset has never been particularly compelling - it's a technology that's only
useful to gamers, but will barely ever give worthwhile performance in
video games.
Okay, now for some really interesting power consumption
numbers!
Videocard Power Draw
Comparisons
Here's how the Foxconn A7DA-S motherboard stacks up in
real life against a couple different platforms, with respect to overall power
draw. PCSTATS measures the total system power draw and compares that in Prime95
loaded, 3Dmark06 loaded and idle states (at Windows desktop). The power supply
used in each test is an A-PFC compliant PC Power & Cooling 750W model.
 System Power Draw
Tests: (PCPower 750W PSU) |
| Desktop Idle (W) |
Watts |
Ranking |
| Intel DG45ID
(Intel G45 200/800 C2D E6750 GF 8800GTS 320MB) |
135 |
   |
| Intel DG45ID
(Intel G45 200/800 C2D E6750 Onboard G45 ) |
68 |
|
 Foxconn A7DA-S (AMD 790GX 200/800 AM2 X2 5000+
GF 8800GTS 320MB) |
131 |
   |
| Foxconn A7DA-S (AMD 790GX 200/800 AM2 X2 5000+
onboard HD 3300 video) |
61 |
|
| Prime95 Stressed (W) |
Watts |
Ranking |
| Intel DG45ID
(Intel G45 200/800 C2D E6750 GF 8800GTS 320MB) |
199 |
|
| Intel DG45ID
(Intel G45 200/800 C2D E6750 Onboard G45 ) |
121 |
|
| Foxconn A7DA-S (AMD 790GX 200/800 AM2 X2 5000+
GF 8800GTS 320MB) |
192 |
|
| Foxconn A7DA-S (AMD 790GX 200/800 AM2 X2 5000+
onboard HD 3300 video) |
121 |
|
| 3DMark06 IGP Stressed (W): |
Watts |
Ranking |
| Intel DG45ID
(Intel G45 200/800 C2D E6750 GF 8800GTS 320MB) |
227 |
|
| Intel DG45ID
(Intel G45 200/800 C2D E6750 Onboard G45 ) |
115 |
|
| Foxconn A7DA-S (AMD 790GX 200/800 AM2 X2 5000+
GF 8800GTS 320MB) |
223 |
|
| Foxconn A7DA-S (AMD 790GX 200/800 AM2 X2 5000+
onboard HD 3300 video) |
124 |
| |
The Foxconn A7DA-S motherboard doesn't draw a whole lot
of power, in large part due to the smaller 55nm fabrication process of the AMD
790GX chipsets. When a mid-range discrete graphics card is added the power draw
doubles, but is still more than manageable even with an economical 400-500W
power supply. Most interesting here is that at idle with it's HD 3300 videocard
in use, the entire Foxconn A7DA-S test PC system sips a little over 61W power,
under the stress of Prime 95 that value doubles to 121W.
Blu-Ray and High Definition content CPU load tests are next.... the lower the
CPU load the less chance of skipping or jittery HD video playback. Let's see how
the Foxconn A7DA-S motherboard handles Blu-Ray playback and VC1 decoding with
it's AMD HD 3300 IGP alone!
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