5 out of 5 stars

>= 128 GB version: Very fast stick

Real speeds in classic Windows 11 usage (512GB version):
Read: 220 MB/s
Write: 240 MB/s < 2GB ; 80 MB/s > 2GB.

This HP x770w 512 GB USB memory stick is really fast, has a nice design, it is small, has no caps so you cannot lose it, and it locks once you have opened it, so you can insert it easily and remove it easily.

The speed matches the specification, which is 400 MB/s for reads and 250 MB/s for writes, but only with Crystal Disk Mark software on Windows, else slower like shown above.

Speed depends a lot on the stick size so >= 128 GB advised:
Stick size [GB] : Read [MB/s] - Write [MB/s]
32 : 75 - 30
64 : 75 - 30
128 : 200 - 100
256 : 400 - 180
512 : 400 - 250

Details for big files on an NTFS partition:

READ:
If you read a 10 GB file you will get 220 MB/s mean speed for the whole file. It goes up to 280 MB/s max but is usually slower. After about 6 GB, it will drop to 180 MB/s, and then 150 MB/s, and then 120 MB/s.
But 220 MB/s read speed is still very fast for a USB stick even if the specification is not met.
However Crystal Disk Mark shows a read speed of 382 MB/s, almost meeting the specs.
Random 4K: 12.2 MB/s ; 2974 IOPS

WRITE:
If you try to write 2 GB on the stick empty in NTFS, you will get 240MB/s. However with a few files on it it goes down to 112 MB/s. Then if you write bigger files than 2GB or so, it goes down to 80 MB/s mean value minimum. So for a 10 GB big file it reaches 93 MB/s mean speed. That is much slower than the specification.
However Crystal Disk Mark shows 256 MB/s, even exceeding the spec.
Random 4K: 3.2 MB/s ; 794 IOPS

The 256 GB version should provide the same results, except the write speed specified at 180 MB/s instead of 250 MB/s.

WARNING: Versions with 32GB / 64GB sizes have a VERY bad write IOPS:
Read RND 4K: 7.9 MB/s ; 1929 IOPS
Write RND 4K: 0.0 MB/s ; 0.2 IOPS

So the stick is really fast if size >= 128 GB and still very cheap.
It is also a very small, practical and nice looking stick.

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