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

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Potentially the worst CPU bottleneck in computing history.

GeForce RTX 5090 Founders Edition
(Image credit: Nvidia)

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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Mark Tyson
Mark Tyson
News Editor

Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.

4 Comments Comment from the forums
  • salgado18
    Pfff, a Core 2 Quad... didn't have the guts to use a Core 2 Duo, then? The bet is still on the table!

    Also: benchmarks! (never going to happen, I know)
    Reply
  • BloodyBonzai2
    If you run a game like the original Crysis 1 in 8K or 12K max settings, the bigger issue will be the bottleneck from using PCIe 2.0. Really cannot say it will always be a CPU bottleneck when increasing the resolution alleviates the burden from the CPU.
    Reply
  • aberkae
    BloodyBonzai2 said:
    If you run a game like the original Crysis 1 in 8K or 12K max settings, the bigger issue will be the bottleneck from using PCIe 2.0. Really cannot say it will always be a CPU bottleneck when increasing the resolution alleviates the burden from the CPU.
    Lol I ran metro exodus on a 10 year old i7 980xe at 4.3 ghz all cores at extreme settings with 1080ti ftw hybrid at 3440x1440p and got a 60 fps experience. I decided that decade old experiment is over and paired my 5090 by PNY with 9800x3d to mitigate any bottleneck. Fackers are charging thousands of dollars for every inch of performance gained in the gpu side now. Why mitigate that performance with a cpu/pcie bottleneck especially when you can get a 9700x b650e and 32 gigs of ram all under $430 via microcenter now.
    Reply
  • FunSurfer
    BloodyBonzai2 said:
    If you run a game like the original Crysis 1 in 8K or 12K max settings, the bigger issue will be the bottleneck from using PCIe 2.0. Really cannot say it will always be a CPU bottleneck when increasing the resolution alleviates the burden from the CPU.
    ...and it will be a PCIe 1.0 bottleneck if using RTX 5060 as it has only 8 PCIe lanes... and if the system supports only PCIe 1.0 to begin with, we will get AGP performance again!
    Reply