What's wrong with my SSD?

[unohowitis]

I just tried to transfer about 60GB of files from NVME drive D (Kingston PCIe 4 SNV2S 2TB) to NVME drive C (Crucial PCIe 4 P3 Plus 4TB) and got some very unexpected results.

Transfer speed began at 2-3GB/s but immediately dropped to a few MB/s, jumped between almost zero to 100MB/s for the majority of the rest of the transfer. Drive C is supposed to be a fair bit faster than drive D but during this time drive C was at 100% utilisation while drive D was 0-1% utilisation.

The whole PC also ground to a halt, would take forever to load a basic web page or even using file explorer.

During the transfer I had a couple of apps open but effectively idling. Nothing downloading or working in the background. Task manager showed system was using around 5.6MB/s of drive C, all other applications 0.0MB/s.

Looking at the S.M.A.R.T. data everything is showing as fine on the drive, no failures and only at 3% of its use life, I've only owned it a few months. There is 550GB free of 4TB. It also houses the Windows 11 OS.

System specs;
Motherboard: Gigabyte Z790 Aorus Elite AX
CPU: Intel Core i7-14700k
RAM: 32GB DDR5 ~50% free - VRAM ~50% free
GPU: Nvidia 4080 Super
Storage: as above

Both drives are installed directly into the motherboard so I thought a direct transfer like this would be much faster, and at least not slow the whole system down so much that the PC becomes unusable. What might be going wrong here? Thanks very much in advance for your help!

[Lardman]

Transfer speed began at 2-3GB/s but immediately dropped to a few MB/s, jumped between almost zero to 100MB/s for the majority of the rest of the transfer.

Low / No cache budget drives are useless for large file transfers they spend all their time buffering.

[unohowitis]

aha OK thank you. So that would be for when writing to the drive but it looks like this is not the case when sending data from the drive ie. reading correct?

Also, would activating Crucial's Momentum Cache feature solve this? Is Momentum Cache just Crucial's term for host memory buffer? Crucial doesn't mention HMB at all but from my reading it appears they are the same function?

[Lardman]

No idea about vendor specific software caches. There's a good reason why drives like these are 1/2 the price of decent ones, you're trying to get Ferrari performance out of a Ford.

If you're doing artificial speed tests forget them and check if the drive is fast enough for your real world use. If you're moving large files around all the time you will need a better drive, the budget ones are designed for gamers sporadically burstloading smaller assets.