Our regular readers may remember that by closing the bridges on the chipset North Bridge we could make nForce4 chipset support SLI and SATA-300 turning it into an analog to more expensive solutions. Keeping in mind that the new nForce 5xx series of chipsets are single-chip solutions based on nForce 570 SLI chip, the idea of modifying it is also very tempting.

The first experiments of the kind have been performed by our colleagues from HKE_PC site. They may have never decided to undertake transformations like that if it hadn't been for the Magic-Pro A2N5 mainboard on nForce 550 chipset that supported the SLI mode despite the nominal features of the chipset. The further investigation followed the already familiar algorithm. The thing is that the origin of nForce 5xx chipsets allows the mainboard makers to retain the PCB design when they shift from one mainboard model to another. All excessive functions are simply blocked on the hardware level. If we compare two mainboards with the same design but based on different chipsets, we can find these differences and then unlock the necessary features.

Of course, first of all we took a closer look at the chipset and the bridges on its packaging. The difference between nForce 550/570 and nForce 570 SLI and nForce 590 SLI was evident: chipsets with SLI support had no resistor in the position marked with red circle:

However, removing this resistor didn't let you use the second PCI Express x16 slot, because it simply wouldn't let the second graphics card work in PCI Express x8 mode. They had to look for other differences in the mainboard design. By comparing two MSI mainboards our colleagues managed to find those differences: they discovered two groups of elements around the chipset North Bridge and the second slot. They are marked with red on the pictures below:

It was even more complicated because the nForce 570 based mainboard didn't have all these switches, so the guys had to remove those elements from the ?donor?mainboard based on nForce 570 SLI chipset onto the mainboard that didn't have them. Of course, this modification technique is hardly suitable for mass home experiments.

When the resistors have been moved over, the system thought that it was dealing with nForce 590 SLI chipset, which automatically changed the second PCI Express 1x slot to PCI Express x8.

Now, even the driver thought that it was an nForce 590 SLI based mainboard, so SLI mode was enabled:

The modified mainboard demonstrated the same performance level as its fellow board based on a real nForce 570 SLI. Theoretically, this transformation allows saving about 50% of the mainboard cost. The only problem is that this modification is extremely complicated and may be dangerous for the board. Secondly, there are not so many mainboards on nForce 550 and nForce 570 chipsets that will boast two PCI Express x16 slots. Although they will probably be able to accommodate GeForce 7950 GX2 graphics card that implements SLI principles by using only one single PCI Express x16 slot and a chipset supporting SLI technology.