Does my BitLocker Use hardware acceleration?

Hi all,

Recently I assembled my new computer, key specs for my question:

• CPU Intel i7-7700K
• MB ASUS ROG Strix Z270I
• Samsung 500GB 960 EVO NVMe M.2

One of the reasons why I bought Samsung 500GB EVO is because I red that it supports hardware encryption and i thought all I need to do is to enable encryption in Bios. I appeared that not all the motherboards support Self-encrypting drives, particularly motherboard I've got does not have and option to set SSD password.

Well, I was disappointed but my research has shown that BitLocker, built-in Microsoft tool should support SSD's hardware's capabilities of encryption and supposed to use hardware-backed encryption when I use BitLocker with no performance impact.

So I encrypted both my partitions (C and D drives, located on the same 960 EVO drive). It looks like it works fine so far: I need to enter password just once before Windows boot and for drive D I enabled auto-unlock feature, so from user point of view it works seamlessly.

The only question I got is performance impact

So trying to figure out is my BitLocker really uses hardware acceleration and check is there really no performance impact I measures SSD speed with CrystalDiskMark, and results little confused me:

First, couple screens before I enabled BitLocker (actually screens were taken couple weeks ago)



And now screens after I enabled BitLocker:



As you can see:

Read

• Seq Q32T1 is down from ~31000 to ~28000
• 4K Q32T1 is down from ~800 to ~620
• Seq is Up from ~1500 to ~1800 (!)
• 4K is Up from ~35 to ~40+ (!)

Write

• Seq Q32T1 is up 1600 to 1700
• 4K Q32T1 is ~600 to 830 (!)
• Seq is about the same or slightly higher
• 4K is about the same

UPD: I noticed that I forgot to test drive C after BitLocker was enabled, so adding the screen.
Interestingly enough, it shows much better Seq Q32T1 speed than drive D



So, I do not understand:

• Why some tests dramatically dropped while other dramatically improved?
• It is still not clear to me, does BitLocker use hardware encryption or not (uses CPU)
• Should I think about these drops as about performance degradation or not (because I also got some improvement)?

With this result, honestly, I do not think I will see the any difference, because anyway these numbers much higher than I get on other computers with SSD, for example my work laptop, brand new Dell XPS 15 (with no BitLocker) is not even close:



But anyway, those questions above do not let me rest,
can someone make sense for me out of it? :)

Thanks!