RTX 5090 with Core 2 Duo? Nvidia driver change opens up bizarre system build options

Nvidia's newest drivers no longer require the system CPU to support the POPCNT instruction. We don't know why this change has been made, however, there are some fascinating implications regarding what you might call mismatched hardware. For example, tech enthusiast Bob Pony observed that due to this driver change, "you could possibly pair an [Nvidia GeForce] RTX 5090 with [an Intel] Core 2 Duo." We'd like to see it, and surely we will see this exact scenario tested by a TechTuber, shortly.

In Pony's screenshot (unfurl the post embedded above) you can see what appears to be an Intel Core 2 Quad Q9650 processor powered system running a version of Windows 11 Pro. That alone might need some system hacking shenanigans. However, Pony asserts that the latest Nvidia driver, version 576.40 which was released just yesterday, now plays nicely with systems packing old Core 2 Duo CPUs (introduced 2006) which lack POPCNT support.

The tech enthusiast included a post later in the thread to show that Nvidia didn't support system CPUs lacking the POPCNT instruction when he checked last August. In fact, unfortunate users trying such an installation might face a 'soft brick' and have to wait through a number of boot loops before being able to recover Windows startup.

So, what is POPCNT?

POPCNT is a CPU instruction and a short form derived from Population Count. Processors use it to determine how many bits are actively set in a given binary number. Notably, it is part of the SSE4.2 instruction set. Given that you have to go back more than a decade and a half to find processors without native POPCNT support, it doesn't really concern anyone who wants a practical workmanlike PC for typical 2025 workloads.

Windows 11 24H2's POPCNT requirement

POPCNT may seem like an obscure processor instruction, but it has been in the news previously, with popular software insisting upon it being supported by the system CPU. Case in point - Microsoft's Windows 11 24H2 introduced a requirement for POPCNT hardware support. That change came to light around a year ago, and alongside other requirements such as tech as secure boot and TPM support, it ruled out a host of older CPU generations from official Windows 11 OS compatibility.

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