The short answer is probably not.
There is however a more complicated answer: Truthfully the rated speeds for SATA III and USB 3.0 really
aren’t that different, 6 Gb/s versus 5 Gb/s respectively (NOTE: little “b” is for bit and 8 bits make a Byte
or a big “B”). That’s not a huge difference and to further muddy the waters they need to be encoded,
SATA III drops to 4.8 Gb/s after you account for the speed lost to encoding it works similarly for the USB
drive as well. Typically internal SATA III SSDs max out that rated 6 Gb/s and there are definitely external
USB SSDs that max out that rated 5 Gb/s as well (NOTE: external HDDs will be slower still). So your
internal SATA SSD is going to be roughly 17% faster on average than an external USB 3.0 SSD.
Unfortunately from here onward the answer becomes more complicated still. There are still more types of
USB port to account for: USB 3.1 Gen 1, USB 3.1 Gen 2, USB 3.2 Gen 1, USB 3.2 Gen 2, and the poorly
named USB 3.2 Gen 2x2, plus USB 4.0. As a point of clarity USB 3.1 Gen 1 and USB 3.2 Gen 1 are
functionally just renamed versions of USB 3.0 so they are still 5 Gb/s. Where there are faster USBs there
are also faster internal SSDs PCIe Gen 3, PCIe Gen 4, and PCIe Gen 5 most will know those as M.2
NVMe drives.
The fastest of the USB ports that are accessible as of this moment is USB 3.2 Gen 2x2 it is exclusively a
reversible Type-C port and hits a rated speed of 20 Gb/s, USB 4.0 hasn’t gotten a full release as of yet
and is also exclusively a reversible Type-C port and rated for 40 Gb/s. USB 3.1 Gen 2 and USB 3.2 Gen 2
both rate 10 Gb/s. NVMe SSDs are typically rated in MB/s (that’s a big “B”, 8 bits make a Byte and 1000
MB make a GB). Drives that use four PCIe lanes at Gen 3 are capped at 28 Gb/s (3500 MB/s) reading and
writing, Gen 4 using the same four PCIe lanes are capped to 56 Gb/s (7000 MB/s), and the just released
Gen 5 can hit speeds up to 112 Gb/s (14000 MB/s).
That endless list of numbers basically says that the fastest external USB SSD available today (USB 3.2
Gen 2x2) is 29% slower than the slowest conventional NVMe (PCIe Gen 3 x4) and a staggering 82%
slower than the fastest NVMe (PCIe Gen 5 x4).
But wait that’s not all... Frankly the Universal Serial Bus (USB) is a crowded place all those devices can
end up sharing limited bandwidth, so things rarely operate at rated speeds over USB. Longer cable runs,
not just outside your PC but inside as well add more signal noise which can cause errors and slow things
down further. Finally USB devices need to be deigned with being handled in mind, that means drops and
shocks first and speed later. Usually that still isn’t enough to stave off long term damage, if it is something
you want to keep or back-up it probably shouldn’t be on a portable drive or USB flash drive.
With that, should I run video games off of an external HDD or SSD? If you are on an older PC with no
NVMe support it is probably harmless, but a SATA SSD will probably be less expensive. If you are on a
new PC with an NVMe drive you should definitely consider ditching the external if space permits.