NVIDIA nForce 790i SLI chipset architecture

As we covered the nForce 790i chipset in detail in our Striker II Extreme review, for this article we'll stick with just a brief overview of the architecture before explaining the differences between nForce 790i SLI and 790i Ultra SLI parts.

Starting with the real basics, nForce 790i now officially and completely supports the 1600MHz FSB speed used by Intel's latest Extreme Edition CPUs, meaning that their full range of Core 2 parts are now supported in their entirety.

The basic PCI Express configuration remains more or less the same from that seen in nForce 780i (although overall there are two less PCI Express lanes available to nForce 790i).  This means that 3-way SLI support remains via the nForce 200 chip, and in the same fashion as seen previously, via two 16x PCI Express 2.0 slots coupled with a single first generation PCI Express 16x slot.  That leaves the southbridge with an additional eight PCI Express lanes to dish out as required.

The PCI Express bus, and more particularly communication between CPU and GPUs in an SLI configuration, also gets some added attention in nForce 790i, courtesy of two new features introduced with this chipset.  The first of these features is known as 'PW Short' - This is basically a point-to-point communication scheme between GPUs in an SLI configuration, so that any messages can be sent from one graphics board directly to its destination without having to traverse any other part of the system.  This should help in reducing latency when GPUs need to 'talk' to one another, and also remove congestion on the link between system memory and the PCI Express bus that this data would usually have to be processed through.  The second new technology is known as 'Broadcast', and is designed to reduce communications over the FSB while reducing latencies for data sent between the CPU and multiple GPUs in an SLI configuration.  In multi-GPU systems, the CPU often needs to send the same data (particularly geometry and texture data) to each GPU, meaning that the same data is sent across the system multiple times, once for each graphics board.  Broadcast technology in the nForce 790i chipset allows for this data to be sent only once by the CPU to the motherboard chipset's SPP northbridge, which will then handle ensuring that data is provided to all relevant GPUs on the PCI Express bus.

Easily the biggest change to the nForce 790i chipset however is with regards to memory support, with DDR2 jettisoned from this chipset in lieu of the newer DDR3 standard.  NVIDIA has worked hard on their DDR3 memory controller for the nForce 790i chipset - firstly, unlike Intel's offerings, users can run their FSB and memory in an 'unlinked' mode, allowing for them to be clocked independently of one another.  The chipset also uses a low latency data path for writing and reading between the board's MCP southbridge and memory, together with new algorithms to improve overall data access speeds to and from memory.

Indeed, memory support is the one and only difference between the nForce 790i SLI and Ultra SLI chipset - While the standard nForce 790i SLI officially supports memory speeds of up to 1333MHz, the 790i Ultra SLI can make use of speeds up to 2000MHz.  This can be achieved via a new generation of NVIDIA's 'SLI Memory' scheme, first seen with DDR2 modules and the nForce 680i chipset.  The EPP 2.0 open standard introduced here works in the same way as the original EPP standard used by 'SLI Memory' DDR2 modules, acting as an extension to the SPD (Serial Presence Detect) chip already found on all memory modules to store additional performance and tuning information and the like.  In short then, while both boards support EPP 2.0, the nForce 790i SLI chipset is identical to its bigger brother aside from officially supporting memory clocks above 1333MHz, so if running insane memory clock speeds doesn't interest you, then this chipset will suit your needs without burning quite such a large hole in your wallet.

Away from those architectural changes, much of the core feature set of the nForce 790i matches that of its predecessor, with support for NVIDIA's ESA (Enthusiast System Architecture) for system monitoring and tweaking retained, and a southbridge featuring dual Gigabit Ethernet adapters, ten USB 2.0 ports and six Serial and two Parallel ATA devices.  Azalia HD audio is still present, together with support for up to five PCI slots.

So, that's the reference nForce 790i SLI chipset and architecture in a nutshell, let's now see what ASUS have built from this baseline.

Packaging and bundle

So with the chipset details out of the way, let's take a look at the retail packaging for this motherboard.

Aside from the nForce 790i SLI branding and the replacement of 'Extreme' with 'NSE' (what does that stand for anyway?  Not So Expensive is my guess, but answers on a postcard...), the box art for this product looks identical to every other Republic of Gamers board we've seen from ASUS recently.

The rear of the packaging tells us everything we need to know about this board's specifications and feature set, and picks out some of the product's highlights.  Once more, Company of Heroes: Opposing Fronts is bundled with the motherboard.

Aside from the Striker II NSE motherboard itself, this particular offering comes equipped with a system fan, backplate, Q-Connector, an LCD poster (very handy for figuring out potential issues at boot time), and the usual handful of Serial ATA cables.  Alongside the motherboard's driver DVD, we also find our bundled copy of Company of Heroes: Opposing Fronts, and a couple of SLI connectors for both two and three-way NVIDIA board SLI operation.  All the connectors you should require for hooking the Striker II NSE's cooling setup to a water cooling system are also included to round off the bundle nicely, as this part features the same Fusion water block system as the Striker II Extreme.