Enterprising software hackers have figured out how to unlock NVIDIA’s SLI for the Intel P965, P35, P45, X38 and X48 chipsets as well as the AMD 790X chipset. This means that motherboards which previously offered no SLI support can now give it a go.

Busting the SLI routines open for SLI-uncertified boards has been a multi-year endeavor. As late as November of last year, NVIDIA buried encrypted routines deep in their GPU drivers to detect SLI-certified boards. These routines were backed by a list of vendors which had paid NVIDIA a nominal fee for a place on the list. If the detected motherboard matched a board on the list, then SLI was activated in the video driver. Driver modders were never quite able to break the encryption to fool that routine, but the advent of Intel’s X58 chipset changed the game.

Intel’s X58 was the first from the Santa Clara firm to receive SLI certification, and it took months of petty squabbling to make it happen. Prior to its market debut, only a small selection of NVIDIA boards had that honor, but soon there would be hundreds. Rather than release a new driver to update the SLI list for every new motherboard, NVIDIA appears to have simply changed the routine. Recent NVIDIA GPU drivers have abandoned encryption in favor of plaintext strings and IDs to check for X58; if X58 exists, SLI is a go. Pretty simple, especially for driver hackers.

Changes to the detection methodology has empowered driver hackers with the ability to make any motherboard report back with an Intel X58 ID. And because all X58 boards are SLI certified, that means all of your boards with two PCIe x16 slots can be too.

The process of fooling the drivers can be done in one of two ways:

1. Modify the the registry’s ACPI DSDT block to include the SLI certificate from the ASUS Rampage II Extreme motherboard. The DSDT block is a component of the system’s hardware detection routine that reports the system’s most basic specifications. These specs happen to include SLI compatibility. This method requires a modified driver.
2. Modify the registry’s ACPI DSDT block to include the Rampage II’s SLI certificate, then modify the Windows HAL to report an Intel X58 chipset when polled to report the system’s hardware. This process does not require a modified driver and is the more “permanent” of the two.

Both hacks are good for all supported versions of Windows, but the authors have not yet finished writing the procedure for the second.

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