Does gaming off a USB3 SSD impact CPU?

[Cali3350]

Hello.

I just want to say that my assumption on this is that any performance impact is negligible, however I am not positive, and a google search result shockingly gave me no firm information.

A good External USB 3 SSD (such as the Samsung T3 - https://www.amazon.com/Samsung-T3-Portable-SSD-MU-PT500B/dp/B01AVF6UQQ) can sustain read performance around ~500MB/s over USB 3. While that is certainly not comparable to the latest internal drives, its still quite good (good enough for me anyway).

What i'm wondering however, is what exactly is the CPU usage of this? I know that USB relies on the CPU for its data transmission handshaking / handling. It is my assumption that on a modern CPU, the performance is completely negligible, and you will almost certainly not see any performance issue from this. However, I haven't been able to confirm it.

Lets take a game like GTA5, that doesn't have load screens, it streams most of the data for its world during gameplay. Will I be constantly using some meaningful % of a CPU in this case, or is all a wash at the end of the day?

Im assuming a wash, but wondering if anyone had numbers. Thanks!

 

[bigdogchris]

Download something like CrystalDiskMark and run a 4GB file on the drive while watching the CPU utilization in task manager. See if there are any additional services getting spiked.

Also, for games and many applications, the low latency and faster random access of SSD's are more beneficial than the sequential speeds.

 

[Sycraft]

It does hit the CPU more than a SATA or PCIe drive would, but then CPUs are pretty fast these days. Also you can reduce that a lot by making sure you have a drive, and USB3 port, that support UASP. That is basically SCSI over USB and is a lot more efficient at sending commands than the old BOT mode that was the standard for USB media for a long time.

Because of all the factors of CPU speed, USB chip, disk controller and so on you'll basically have to try it yourself to get a definitive result. I expect it won't use an excessive amount, but I expect it will use more than an internal drive, which uses basically nothing.