Wow. This thread goes back to 2017.
A lot of members probably associate me with the software as an avid user.
In another thread, I posted a linked PDF white-paper that Romex had published concerning the use of PrimoCache with Optane. It works fine. The benefits may seem marginal, and a matter of convenience.
Today, of course, you can find the right motherboard, chipset and processor to use with a Sammy Pro 980 -- supposedly to avail of those high benchmark sequential reads of 7,000 MB/s. At that point, you could say you have no need for PrimoCache. Or, weighing "need" versus "want", there's not much need.
However, if you have a mix of storage devices or find it convenient to include SATA SSDs and HDDs, you might then want Primo-Cache to speed up those bottlenecks in conjunct with your 980 Pros/EVOs and your RAM.
I'm not in that much of a hurry to update my systems from my Z170 chips and quad-core Skylake/Kabys. Like my car, I like getting some mileage out of the hardware. I don't like so much the prospect of rebuilding software configurations or moving data, although there are ways to make that easier. And I like to do a lot of tweaking and testing before a new system becomes "fully operational".
So PrimoCache is something I use on all my PCs, old and new, in whatever ways the hardware allows.
That being said, the license for a single PC is a lifetime offering that only costs about $30 or so. These days, that's only two Mexican dinners.
Does it create problems? I can say what those might be, but for the price and at minimum, it "does no harm".
The only troubles I've ever encountered related to big-time feature upgrade/updates to Windows 10. I never lost data, never corrupted a disk, and the problem with the feature update was quickly rectified.
There are very few circumstances where you might want to flush the caches. But it doesn't take that long to refill them. You just have to use your computer.
Somebody mentioned in a recent post their reticence about using RAM-caching, particularly in tandem with L2 or SSD caching. Unless you're using very old hardware, it no longer makes sense to use an SATA SSD as a caching drive. You'd do better choosing an NVME of whatever size you want for a cache drive. I use 256GB units for that.
I use RAM-caching and L2/"SSD" caching together in a two-tiered configuration. I have no problem with it. It makes having at least 32GB of RAM more feasible or useable. IF you have entirely stable RAM and a UPS backup for power, you can perhaps take the risk of enabling delayed writes to show higher sequential and random write scores. Maybe it improves performance, maybe it doesn't, but I've never had problems with it.
If you use L1 or RAM-caching, just be sure your memory is 100% rock-solid stable and error free. Not really a lot of trouble to assure something like that.
If you have a lot of SATA SSDs and HDD spinners, you can cache them all to an NVME drive and then to RAM. But the type of data contained on such drives determines whether it's really practical to cache them. I have two 2.5" HDDs -- one for media, mostly music and video; the other for my Macrium backups. Neither one of those needs to be cached, because it shouldn't require higher than HDD speed to access and stream the files. If it does, then make a cache for them.
ADDENDUM -- I see part of this conversation about PrimoCache includes posts I made on a thread about NVME and M.2 -- also very current. So for both threads, here is one more advisory about PrimoCache.
If you are using a program like Macrium Reflect to backup all of your persistent storage -- NVME, SATA SSD and HDD -- a program like Macrium will throw up a message that it is about to start a scheduled backup. I have mine scheduled for every morning at 9AM, excluding Saturday and Sunday. You should have time to bring up PrimoCache and "Pause" all the caches, one after another. Basically, I have only two cache tasks, and this is pretty easy.
The reason you might wish to do this is straightforward. If you are going to back up storage media that is cached, and especially for a full backup or differential backup, you're going to read a lot of data from the source disks, and it's going to fill your caches, pushing out the data you want in there for programs and files you access frequently. So you pause the caches to keep that from happening.