Asus Extreme N7800GT Dual in the test: SLI for high-end customers on just one graphics card

Asus Extreme N7800GT Dual in the test: SLI for high-end customers on just one graphics card


Asus Extreme N7800GT Dual

If you get the Asus 'Extreme N7800GT Dual' out of the nice big box, one thing is immediately clear: this is a new record in length! The entire card measures a full 25 cm - will it work well when it is installed in the housing? It will, but first we had to remove a plastic holder for the plug-in cards, otherwise the Asus adaptation would simply not have fit in the tower. What kind of a real 'monster' from Asus is it anyway? The Extreme N7800GT Dual is the firstGraphics card in the world that combines two GeForce 7800 GT chips on one card and can also operate them in SLI mode in order to significantly increase rendering performance.

Asus Extreme N7800GT Dual

Since this is, among other things, a quite complex and, above all, expensive PCB as well requires an extravagant cooling solution, Asus has decided to only bring this card onto the market as a 'Limited Edition' with a limited number of 2000 units. As a nice gimmick, the well-known manufacturer labels the cooler with a number that identifies which copy you are holding in your hands - we were sent the fifty-third card, but due to the label 'for media review only' it will hardly reach retailers - the available circulation should be well below 2000 as well.

The cooling system used in the N7800GT Dual is noticeable, which is not only provided with a striking design, but also wants to draw attention to itself through its sheer size. However, the cooler is not one of the heaviest of its kind. The two 7800 GT GPUs and the memory are protected from overheating with a large, passive heat sink made of blackened aluminum. The built-in fan is unfortunately not convincing. It is equipped with a flexible fan control from Asus, which can adjust the speed of the propeller almost continuously depending on the temperature and which is extremely quiet under Windows. Under load, however, it shows its dark side and draws attention to itself with a clear noise level.

Size comparison N7800GT Dual against GeForce 7800 GTX
Size comparison N7800GT Dual against GeForce 7800 GT
Rear N7800GT Dual

Since the two GPUs alone need 150 watts of power in extreme cases and the PCIe slot including the obligatory power plug are unable to provide this performance in an emergency, Asus equips the dual GPU card with an external power supply, as 3Dfx did a long time ago with the never-released Voodoo 5 6000. The power supply unit is connected to the connection provided, which is mounted on the slot cover, and a cable, which is led through a metal rail, conducts the current directly into the usual power connection of the graphics card. The 'additional power' is not optional. The card does not start without the power supply!

passive heat sink on the voltage converters
number 53 of 2000
Slot bracket N7800GT Dual

The two GeForce 7800 GT GPUs are overclocked to 430 MHz by Asus on the N7800GT Dual. The GDDR3 memory from Samsung, which has an access time of 1.6 ns and works at 600 MHz, runs 20% above the nVidia specifications - so the unusual Asus adaptation has the clock rates of a GeForce 7800 GTX, but still does has an additional pixel quad and another vertex shader. Each chip has a total of 256 MB of memory available, but this is not automaticcorresponds to a 512 MB card - even if this is what marketing would lead you to believe. As with a normal SLI team, the entire textures must be available in both memories for the GPUs, since these work together on one image depending on the rendering mode. For this reason, you have to continue to talk about a 256 MB card.

Power connection
Power connection N7800GT Dual
Power cable N7800GT Dual

The graphics card has a TV output that also has ViVo functionalities. A somewhat unusual approach is taken with the monitor connections: While current high-end graphics cards have two DVI connections as standard, Asus not only uses these two DVI ports, but also two D-Sub connections that open two supplied panels are attached. However, these were still missing from our derivative, but will be included in the finished cards for sale. This means that with the SLI mode deactivated, four monitors can be operated simultaneously on the dual GeForce 7800 GT! In addition to the power cable, the card comes with two DVI-to-D-Sub adapters and a cable whip to connect the PC to the television using an S-Video or composite cable. In addition, a YUV output for HDTV playback on a corresponding output device can be found on the breakout cable. The right connections for the video-in functions are not missing either.

Heat sink removed

The software packageis a bit disappointing in the Asus Extreme N7800GT Dual. Although the inserts are overall good average, the size is too small for a card that - be careful, watch out - relieves the wallet by a mere 869 euros. In addition to a multilingual manual, the buyer will find further instructions on a CD and the required drivers in the box. In addition, the software Asus 'Power Director 3DE', 'AsusDVD', Asus 'Virtual Drive', Asus 'Media @ Show SE 2.0' and the two average games 'Xpand Rally' and 'Project Snowblind' are in the packaging. Asus has added a leather-bound folder for CDs as a special supplement.

N7800GT -Dual power supply
heat sink disassembled
GPU-Core - G70

So that the Card also works properly, an SLI mainboard must serve as a support. The boards Asus P5ND2-SLI Basic, Asus P5N32-SLI (BIOS update required), Asus A8N-SLI, Asus A8N-SLI Deluxe, Asus A8N-SLI Premium, Asus A8N32-SLI Deluxe, have been approved for the N7800GT Dual. DFI nF4 SLI-DR and Gigabyte GA-K8NXP-SLI.

On the next page: Test system