There's a few words there I want to be careful with: compatible, available, and recommended.
It's not the OS that you're running into compatibility issues with. Instead, it's the physical memory. The error is a check in place to ensure you can't go beyond what the application can handle. If you're not careful, you have the potential to run into memory faults. The check is in place to ensure you are never in that position. It's compatible with the 64-bit OS. It's just not recommended.
If we look at the product pages for frame grabbers, you're correct the card is available. Seeing that you've had it long enough to use it on a system with XP, I suspect you've had the device for a period of time. If we take a look at the product page for the PXI-1428: https://www.ni.com/en-us/support/model.pxi-1428.html We see the first bullet point is this is not recommended for new designs. Granted, this isn't on the PCI-1428 as well as the newer devices have transitioned to PCIe (which is what we'd expect to find in newer systems). If we look at the recommended upgrade, there's a comparable PCIe-1433 device that would share that same recommendation. If it's not recommended, why is it still available? This is mostly to allow older designs to have replacement parts. It's similar to buying a car. Ford has a newer style of Mustang that requires different parts than the 2002 Mustang. But, it still makes sense to make parts for those customers that still drive the 2002 Mustang. If you're looking to buy a new car today, you're probably better off getting one designed more recently.
Now, we want to take a deeper look at the problem. There's essentially two problems here we need to address. The first is the potential for memory faults. There are two ways to handle this. The first is to throw an error when this may happen. This is the error you're running into by having more than 3GB of RAM. The other is to carefully manage your buffer using the imgCreateBuffer() and imgDisposeBuffer() commands. This one requires more work on your end. If you want to use the second option, you'll need to disable the RAM check. If you don't want to manage your memory manually, you'll need to reduce your RAM to 3GB or less. This is not the recommended option for a system that is only running your vision application. It's not recommended because you're not going to be able to make use of the additional RAM in the application you're using so maintaining the extra RAM isn't offering a benefit. But, it does create a potential pitfall and more work for you.
Ultimately, the decision on how to proceed is yours. You have two paths you can take. I trust you'll make the best decision for your situation.
