Variable USB performance from my Desktop

Davidmball

Novice Member
I use a Foktech Wifi Dongle, AC600 802.11ac with my desktop PC, which has an Asus H81M-Plus motherboard, with the Intel H81 express chipset. I use Virgin media for internet access and have their 200Mb/s service, which I easily achieve with my laptop with an n class adapter (160 to 210Mb/s) on speed tests. However with my desktop, the results are far worse and vary greatly, depending on which USB socket I plug the dongle into. I have USB 2.0/1.1 and USB 3.0/2.0 ports on the back of the PC, 2 USB 2.0/1.1 ports on the front and a USB 3.0/2.0 expansion plate plugged in to the motherboard. With the rear hard wired ports, whether they are USB 2 or 3, I can only get about 15-30Mb/s – it varies from port to port. Using the USB 3 expansion plate, I can get only 4Mb/s download speed, which is less than half of the measured upload speed. My best result, is in the front USB port, where I can get between 30 and 60Mb/s (it varies, depending on which test I use).

The 30-60MB/s download speed is fast enough for my needs, but I would like to know why my desktop performs much worse than my laptop and why the USB performance is so variable.

I also experience variable transfer speeds, when transferring a bunch of small files from the internal HDD to an external USB 3.0 hard disc. The best I can get from the USB 3.0 ports is about 2 x the speed from the USB 2.0 ports. I have checked the USB drivers and they are reported as up to date.
Can anyone shed any light on the cause of the issue?
 

EndlessWaves

Distinguished Member
~60MB/s for smallish files to an external hard drive is likely a limitation of the drive's write speed, not a transfer speed limitation. Write speed does vary with file size. This is mainly because the overheads to transfer files take up a bigger proportion of the time for smaller files, and only file data being transferred is used for the transfer speed number.

The laptop will have a bigger and better aerial than the one crammed inside that tiny case, and will likely have a 2x2 or 3x3 radio compared to the 1x1 of the dongle.

The aerial in the laptop will also likely be better positioned most of the time, which may well account for the speed differences you're seeing between front and rear ports on the desktop - the front ports are likely surrounded by less metal to interfere and are often higher up off the ground.

Tiny dongles in plastic cases can have heat limitations with performance varying depending on how hot they are so that's potentially also a factor.

I'm not sure about the 'expansion plate'. Do you mean something internal or a back plate where an expansion card would normally go?
 

Davidmball

Novice Member
A good point about the aerial position. My Desktop is on the floor, so the rear ports are very low down. The USB expansion ports are on a backplate, at the bottom end of the case, so I would expect similar, if perhaps slightly slower, performance to the ones on the motherboard back plate, not a tenth of the speed.
The 60Mb/s I mentioned was for maximum download speeds from the internet, not file transfer speeds. I did not measure those. I just did a test with a stop watch and the same batch of files, using different USB ports. Given the industry quoted speed difference between USB 2 and 3, I expected a greater difference than I actually get.
 

EndlessWaves

Distinguished Member
The 60Mb/s I mentioned was for maximum download speeds from the internet, not file transfer speeds. I did not measure those. I just did a test with a stop watch and the same batch of files, using different USB ports. Given the industry quoted speed difference between USB 2 and 3, I expected a greater difference than I actually get.

USB2 maxes out at around 30MB/s for file transfers, which is where the 60MB/s comes from.

USB3 is capable of transferring files at 400MB/s but that data has to go somewhere and if the computer can't read it fast enough or the external drive can't write it fast enough the transfer rate will slow down to what the slowest of the pair can handle.

In this case 60MB/s is about the maximum speed you'd expect a hard drive to be capable of writing small to medium files at. If you wanted a higher transfer rate you'd need to replace it with a faster external drive like an SSD.


I'm not sure why the internal motherboard USB ports and the back plate are that slow.
 

Davidmball

Novice Member
Thanks for your input. I am considering investing in power link ethernet, which should give me better and more consistent internet performance.
 

DavidG1

Active Member
Thanks for your input. I am considering investing in power link ethernet, which should give me better and more consistent internet performance.
Not necessarily, Powerline adapters also give variable performance - there are 3 factors affecting this.
  1. The distance between the pair of devices
  2. The complexity of the building’s mains wiring
  3. Electrical noise generated by other mains powered equipment
take no notice of the headline quoted speeds, expect about 1/4 real world rates under optimal conditions, even less the further the distance and if you are on a different ring circuit. I have tried several types of powerline adapters most give disappointing performance and also dropouts.
I would favour a wifi mesh system with a decent PCI-e internal wifi adapter with wired aerial.
 
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