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Question Windows throttling ethernet speed

E

Exoo

Junior Member
I should be getting gigabit speeds, when I test with speedtest I get around ~140mbps, fast.com shows 300ish, sometimes 400.

My NIC is set to 1.0 gbps, my network card is not the issue.

I tried a new windows installation on a spare SSD drive, the speeds were instantly 1gbps without problems. This is an issue with something in my windows.

I don't want a new windows installation unless it's 100% needed.

If you need any other info, let me know.

I feel that this is 100% a problem within my windows installation.
I feel like it's throttling, as the tests are very stable and feel like they don't want to go over a certain speed.

**
Solved this issue.

I used the SG TCP Optimizer long ago (when my speeds were 150/15), I reset to default windows settings and now my speed tests immediately hit 900. **
 
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Worse case scenario if you can't fix it, just get another nic from a different brand so different drivers and it should work fine if it's just that particular nic. If not, reinstall windows. 🙁
 
Without knowing the specs of the computer, there isn't much to say about it.

Really though, drivers would be the primary suspect, uninstall and reinstall.
 
Got Dell's "SmartBytes" or AMD's "Fast Stream" drivers installed? Both of those apps/drivers are known to throttle downloads. I suggest fully un-installing them.

If those ARE NOT installed, then do some DEEP (offline, bootable) anti-malware/anti-viral scans. You might have some sort of rootkit, using your connection to send SPAM, part of a BOTNET, etc. that's chewing up your bandwidth.

Can your router display any real-time graphs of bandwidth usage, per-device? I know Tomato can do that, as can AsusWRT on newer Asus routers, as can MerlinWRT as well.

Edit: Or it could be as simple as a NIC configuration setting that's out-of-place, or that the "fresh" Win10 installation, auto-installed newer/better drivers for your NIC, or fresh settings for it, than you have in your current Windows installation.

Edit: If you have some sort of "Internet Security Suite" software installed, that could be causing the slowdown too, in conjunction with CPU load, etc. (Which could be exacerbated by any mining software that might be running in the background. (Check your temps at idle inside Windows, if they are elevated, then possibly you might have either cooling system issues / throttling, or mining malware installed.)
 
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Solved this issue.

I used the SG TCP Optimizer long ago (when my speeds were 150/15), I reset to default windows settings and now my speed tests immediately hit 900.


The setting responsible was this command in particular.

"netsh int tcp set global autotuninglevel=normal"

If I set this to disabled (as it was) it throttles my speeds, when it's normal, it works correctly.
 
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