File transfer speed on privae LAN

I'm moving computers and drives around and moving some large files. I'm disappointed in my file transfer speeds and thought to ask out here what kind of speeds you guys are seeing in your Windows home networks.
 
I'm using Windows file explorer and just copy and pasting several GB at a time and I'm only seing about 9 MB/s. There is one managed switch involved, otherwise it is Windows PC to Windows PC.

What is happening is that I start a transfer from computer A to computer B. The speed is approx 9 MBs. Then I start the same transfer from a third wifi computer C and the speed was about 4 MBs. Why is the transfer slower when initiated from a third computer?


 
Mike.

PS - It is a gigabit network with both computers wired to the network.

There's a lot of factors that go into this. Such as RAM, processors etc inside the actual computer too. It's not always the actual internet speed. Just an FYI!

I added a Gb switch a couple of years ago and built a couple of PCs soon after that using motherboards that came with Gb interfaces builtin.  This was my first foray into the Gb world (outside of work).  Forgot the exact speeds that I got, but IIRC I was happy with the results and think it was something like 70+ Gb/s speed.
 
Sounds like you're getting 10Mb speeds.  Verify that your interface details are showing that the device is configured as Gb speed and not 10Mb (including verifying correct driver installed).  Also your switch should have LEDs to indicate configured speed of the port used by each PC (either explicit LED or as mine do by turning on both LEDs when Gb speed is established.) 
 
Finally this could be due to cable quality.  I had a working Gb PC connected to a switch just a few feet away.  I was testing some various cables and some would only work at 100Mb.  All were either CAT5 or CAT5e cables and I had done the termination on most of them.  I replaced the connector on a few and got the Gb speed.  I'd be surprised that it dropped all the way down to 10Mb though, which is why I suspect it's more of a config issue.

I also sent this question to a friend who is a network tech and just heard back from him. He tells me that when I initiate the copy/paste at the source computer the transfer goes directly from source to destination. When I initiate the transfer from a third computer the data takes a path through all three computers.  Sounds like a good explanation to me especially because the third PC is wireless.
 
Mike.

gregking
 
Thanks, I'm going to do some testing and digging around and see what I can learn.
 
Mike.

If you look at my original post you'll see that the actual speed or throughput of the transfer  wasn't my only concern or question. The question was why the transfer was much slower when initiated from a third PC. That is explained by the fact that the transfer is traveling through all three machines. With this in mind I considered the fact that the third machine is not plugged in (wifi). Before attaching a cable to it I switched from 2.4GHZ wifi to 5G wifi and it is much faster, almost the speed ot the original 2 PC transfer.  I must have RF interference on the 2.4.
 
That seemed to satisfy my original question but now I started wondering what gregking said about the speed and that was easier to solve. The source of the data is an old HP Pavilion computer with a 10/100 ethernet adapter. I'm moving ~9 MBs which is 9x8 or 72 Mbs. It's connecting at 100 as it should.
 
Mike.

I just looked at my original post and I screwed that all up. .It was missing  a paragraph or two (that I have since added). I must have accidentally deleted part of it before posting it but I didn't explain what I meant to explain.
 
What was happening was that I would start a transfer from computer A to computer B. The speed was approx 9 MBs. Then I started the same transfer from a third wifi computer C and the speed was about 4 MBs. I meant to question why the transfer is slower when initiated from a third computer. This was explained by the fact that the data travels to all three computers in the second case. I did not know this was the case.
 
I don't know how that got omitted from the original post. I must have dumb thumbed the delete key.
 
Mike.

Just to be clear, most network links are quoted in megabits (not megabytes).  Many (most?) file transfer programs report speed in megabytes. By convention MBS (or MBs or MB/s) is megabytes, and mbs (or mb/s) are megabits.  in simplistic terms 8 mbs = 1 MBS, but it's not that simple.  File transfer speeds are typically quoted at the application level whereas link speeds are at the bottom layer, and there's a lot of overhead (headers, checksums, etc.) that get added, which could be a few percent, or even 20-30 percent depending on protocol and packet size.  I find with windows multiplying by 10-12 is a better indicator than 8.  
 
Apologies if all this was obvious, but the comment about old 10mbs speeds left me wondering.
 
As mentioned, slowness can be from almost any source, and trial and error is your only friend.  A lot of home hardware is really, really cheap (even if it costs a lot of money), ethernet ports on both PC and switches may be slightly flakey.  Retransmissions from flakey devices can have a horrible impact on throughput not because it has to occasionally restransmit, but because it affects dynamic timers that reduce how much data can go into the pipeline.  Having extra equipment to swap helps.  It's also possible (with most adapters) to hook two computers together directly (though it requires you manually assign an IP address to each) and eliminate the switch.

Linwood
 
Thanks for the input. I was careful to compare apples to apples. Windows explorer is what I was using to move the files and it reports in MB megabytes. My slow transfer speed was primarily due to the fact hat the source computer has a 10/100 NIC (which I had overlooked). I later moved some large files between two 802.11ac NIC's and got 40 - 50 megabytes/second which I think isn't bad after taking into consideration all of the things that you mention (wiring, traffic, switches).  It seems fast enough for what I do.
 
What transfer speed should I expect to see from two 802.11ac NIC's with cat5e network going through one unmanaged switch and moving with Windows explorer?
 
Mike.

You can initiate a WiFi direct connection between the two wireless laptops by passing the AP for quicker transfer speeds.
 
This is the base for using Miracast from your smart phone to your television these days.

How to Set Up Wi-Fi Direct Using a PC

This works today with Ubuntu (Linux) or Windows. Windows to Linux; Linux to Windows wireless devices.
 
IE: say you have a media PC directly connected to your LAN and you want to transfer a file from your wireless laptop to your media device.  It will be faster to use Wifi direct to a wireless interface on your media device than to go through your AP.