It doesn't matter either way. For most and that's like 90+% off any task or app you might do or use, most can't take full advantage of those kinds of speeds anyways.

So if you already have a PCIE 4.0 NVME SSD as an OS drive then you're fine to leave that as-is. Use the new ssd to house games. Once you have at least 1x secondary drive, after its formatted and assigned a drive letter you can configure all the major game clients settings and add a game library on a secondary drive so either its the default location for game installs moving forward or is an option when clicking install you would then have option to choose the library on another drive.

Unless you are willing to either wipe out the old drive or backup off of it what you need onto some other drive (not the new ssd though) and then wipe both drives and do a clean OS install on the new PCIE 5.0 SSD then it's not worth worrying about.

Originally posted by Bad Aim:

I just ordered a Western Digital Gen5 M.2 2TB drive. I emailed WD asking them if I should use this as my primary drive or if it would be put to better use if I used it as a gaming drive only. They responded with "That's up to you", which didn't help me.

it does help you. It's up to you, because it doesn't matter how you want to use it. There is no "best". It's just storage, use it how you want.

Although my preference is to install Windows on the fastest drive I have. But seeing as what you're already running, the difference would be fairly inconsequential most of the time.

Originally posted by Bad Aim:

Currently my primary drive is a Gen4 WD black M.2 4TB drive. I'm old school, my first computer being an old 8088; two 5 1/4 inch drives and no hard drive. CGA monitor. The first computer I bought with my own money was a brand new, custom built 486 DX/80.

So based on my personal experience and intuition, I would want to use my new Gen5 M.2 as my primary. This will speed up my operating system and still give me room to put some of the more advanced games on it. (most likely I would use it for VR games.)

But, I honestly do not know for sure. Anyone willing to give me recommendations?

I would generally agree, I would prefer the fastest drive for the OS. However, it's going to be a bit more work to do the cloning or do a clean install of windows and set everything back up. That's up to you. But it would be 99% your preference, and 1% actual performance benefit in most cases.

I might be willing to do that work personally. But I won't pretend everyone should or that there's a lot of measurable benefit beyond my own satisfaction.

Unless you are editing large files, it won't make any notable difference.

Gaming and general computing uses random reads, the crazy performance numbers, are for sequential, as far as random go, the fastest drive isn't much better than a, quality 5 year old sata drive.

As a rule of thumb, you want your OS and its associated things (page file, etc.) on your fastest drive.

As a rule of thumb, you want your applications on your fastest drive.

As a rule of thumb, you want your games on your fastest drive.

As a rule of thumb, you want your stored files being accessed from your fastest drive.

See where this is going? Ideally, you want anything and everything you're accessing to be on something faster as opposed to something slower. When working with tiered storage (meaning it's not all identical and some is faster/slower than others), you don't have that option though.

It's sort of worth pointing out too that on most platforms, the primary M2 drive is connected directly to the CPU and secondary ones sometimes aren't. The secondary ones are often connected to the chipset which itself is connected to the CPU. So what's the difference? Beyond some added latency, this connection uses as limited number of lanes. In particular, AMD platforms only use 4 lanes (recent Intel platforms use 8 as far as I know). Guess how many lanes a single NVMe drive uses? The answer is 4. While the drop is small, it's there. So I'd always have the OS on the primary M2 port as well.

But none of these are hard rules. Just "most efficient average measures".

You haven't stated what drives you're using, only that one is PCI Express 4.0 and the other is 5.0. That doesn't say much.

I'll presume the 4.0 drive is something like an SN850X (one of the fastest 4.0 drives) or a SN770 (fairly performant but more mid-range overall) and the 5.0 could imply it's the new SN8100. The latter would be much faster than either or the other two, but it's mostly going to be peak sequential values.

There's sort of two ways to look at this.

The first is that "it doesn't matter" because even the slowest possible drive here (the SN770) probably won't be blindly discernible compared to the fastest for most uses. For non-power users, that will likely be true.

The second is that if you already have a very performant PCI Express 4.0 drive (already well into "not discernible" territory) and are spending money on a more premium drive, you may as well make use of it all in the best way you can. And the time to clone and switch positions of an SSD is small, which is ultimately what would make me lean towards this option.