NVIDIA's SLI: Part 1 - Motherboards

Overclocking:

We overclocked each of the motherboards using a 6x CPU multiplier, while using a 3:2 memory divider to remove the bottleneck of our memory limiting the motherboards' ability to overclock. We set the HyperTransport multiplier to 3x, to give us enough headroom for high HyperTransport speeds. The low CPU multiplier meant that the CPU would not be a limiting factor in our overclocking attempts, allowing us to paint a more accurate picture of what can be achieved from each of these motherboards. We also dropped the memory timings down to 3.0-4-4-8, to ensure that the memory would not become a limiting factor when we were overclocking.

We found that the ASUS A8N-SLI Deluxe managed to achieve a CPU front side bus of 305MHz before we encountered problems when running the Prime 95 torture test - it would not run error-free above 305MHz HTT. At this clock speed, the memory was running at a little over 203MHz, so it was not a limiting factor in our overclocking experiences with this motherboard.

The DFI LANPARTY nF4 SLI-DR faired much better than the A8N-SLI, achieving a massive 375MHz HTT before encountering problems running Prime 95's torture test. We were able to complete our full benchmark suite with the CPU front side bus at a rather hard-to-believe 400MHz HTT. At that clock speed we ran out of memory, so would have to drop the memory divider to a lower value in order to attain such a high front side bus when using our OCZ PC3500 Enhanced Bandwidth memory modules. AT 375MHz HTT, the memory modules were right on their limits at 250MHz, and we believe that it was the memory modules holding us back at this bus speed.

The Gigabyte GA-K8NXP-SLI fared the worst in our overclocking tests, topping out at 296MHz HTT. It may have been down to any number of things, but there does not look to be the headroom that is available on the DFI. Anything above 296MHz caused errors in Prime 95's torture test during our 3-hour stress test.

Finally, MSI's K8N Diamond overclocked like a gem, achieving a stable CPU front side bus of 352MHz HTT. This may be down to the lack of memory voltage available, but when we tested the OCZ PC3500 Enhanced Bandwidth memory on our ASUS P4P800-E Deluxe motherboard last year during our DDR Memory roundup, we found the memory topped out closer to 245MHz with 2.85v. OCZ's Enhanced Bandwidth memory typically fares better on an Athlon 64-based platform, so we don't believe that this is the limiting factor in our overclock.

Summing things up:

The ASUS A8N-SLI Deluxe has the benefits of being able to add a third party cooling solution to the northbridge, which will enable you to install a waterblock if you are looking to fully watercool an SLI system. In that sense, the layout of the motherboard is a very good one, and you can do many great things with it. On the whole, a solid motherboard with an equally solid bundle, but the BIOS takes a little getting used to if you've never had an ASUS motherboard before.

DFI's LANPARTY nF4 SLI-DR is a very inspired motherboard in many ways, but there are a few quirks that could count against it. Early BIOS revisions on the motherboard had issues with any modules based on the popular Samsung TCCD DRAM's, and we understand that there are still boards shipping with these early BIOS revisions. We know the fact that motherboards are still shipping with early BIOS versions is not necessarily DFI's fault, and we commend them for releasing an updated BIOS to fix these problems in very quick time.

The fact that the NForce4 MCP is located directly under the video cards, means installing a third party cooling solution is not going to be all that easy. However, as we have proven, the stock cooler has enough headroom in it to cause our memory to be the bottleneck when we were overclocking. If you don't mind a little bit of tinkering, by flashing to the latest BIOS revision when you purchase the board, then this board will serve you very well.

The Gigabyte GA-K8NXP-SLI has some interesting technologies on it, such as the 6-phase Dual Power System, which allows for cleaner power to important parts of the motherboard. However, there are installation issues with the DPS card, in that there are a couple of capacitors that are not ideally located. They need to be bent slightly out of the way to install the add-in card. The inclusion of a wireless network card is also another plus point for Gigabyte's motherboard. In general the board is a very fully featured motherboard, with a solid bundle of extras.

MSI's K8N Diamond also has some interesting additions to it that give it an edge over the competition. The addition of a Creative Sound Blaster Live! 24-bit audio chip means that this board features the best onboard sound solution in the roundup. It uses fewer resources than the AC'97 sound chip, and is Creative's budget High-Definition Audio solution, but the downside is that there is no optical-in.

The Diamond Club also looks to be an interesting addition, where you can practically pay for one-to-one technical support, as opposed to the standard technical support lines that can often get jammed up with calls. We're interested to see how well that works in reality. The SLI switch was not the easiest to change - possibly the most difficult of the bunch, but you are likely to only change that once or twice in the lifetime of the motherboard.

If you are not planning to overclock with your SLI platform, any one of these solutions is worth considering. They each have their benefits, and it is just a case of which one suits your needs the best.

Final Thoughts...

Until now, we have not discussed price, because anyone building an SLI platform is likely to have a hefty wad of cash ready to splash out on the best kit available to buy. However, ASUS' A8N-SLI Deluxe is in a completely different price bracket to the other three motherboards. If you are considering building an SLI platform for two GeForce 6600 GT's, this might be a worthy consideration priced at £114.95 on Gladiator Computers.

While we haven't reviewed it here, there is the DFI LANPARTY UT nF4 SLI-D, which is £10 more expensive than the ASUS A8N-SLI Deluxe, and is not quite as feature packed, but it will allow you to achieve some unthinkable overclocks. However, given the features that you get at such a competitive price point, you cannot really go too far wrong with the ASUS A8N-SLI Deluxe, and thus we have awarded it bit-tech.net's Value Award.

Gigabyte's GA-K8NXP-SLI is a solid motherboard at stock speeds, but it just does not live up to the abilities of either the DFI LANPARTY nF4 SLI-DR, or the MSI K8N Diamond, and we feel that there are better alternatives for the enthusiast. However, the bundle may well entice you in to buying the Gigabyte - it's a great bundle, but you have to consider whether the bundle is more important to you than having a board that is capable of so much more.

That leads us to the DFI LANPARTY nF4 SLI-DR and MSI K8N Diamond. Both motherboards are great boards in their own right and they are both priced at £149.95. However, we feel that the DFI just has the slight edge. It's superb. We'd go so far as to say that at the moment, there is no better enthusiast motherboard on the market. It's that good!

If DFI's motherboard did not exist, then MSI's K8N Diamond would be a worthy winner of this group test, and we commend MSI on making a very good motherboard - they've just been pipped to the post by a truly fantastic enthusiasts motherboard from DFI. On that note, we present DFI's LANPARTY nF4 SLI-DR with bit-tech.net's Award for Excellence. There simply isn't a better SLI motherboard out there at the moment.