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I'm stumped as to why one of my computers gets TERRIBLE broadband speeds late at night, and is OK in the morning.

I checked for a scheduled backup or drive scan. There are none.

Speedtest.net shows 1.1 MBpersec down and no upload at all. This typically starts at about 11:30pm and goes into the early morning hours. By 9am it is back to 7mbps down and 2.4mbps uploads.

While this is happening, another computer on the network can get 24mbps down abd 4mbps up.

So it's not the cable provider.

Another thing, the affected computer takes 20 secs to see the router admin page, or the cable modem admin page.

The other computer can see the router and cable modem in an instant while this is all happening. It is fine.

I ran process explorer and only 1% of CPU was in use. Memory was fine, and the network traffic was minimal while the computer is crippled.

BOTH computers run Norton Antivirus and it is up to date. I typically use Google Chrome because I like the "sandbox" design that limits malware access.

Any ideas how to find out why this computer gets so slow?

It's a quad core Duo on an Asus P5Q.

Thanks for any ideas!

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migrated from stackoverflow.com Oct 8 '10 at 20:06

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2  
What has any of this to do with programming? –  Oded Oct 8 '10 at 19:12
    
StackOverflow has a sister site, www.superuser.com, which deals with non-programming questions about general computer topics. Some editor will probably move this question over there, but if not you'll want to go check out that site directly. –  Steve Perkins Oct 8 '10 at 19:15
1  
what operating system? –  studiohack Oct 8 '10 at 20:19
1  
Are these computers connected to your network wirelessly, wired, a mix of both? –  Wagnarock Oct 8 '10 at 20:22
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2 Answers

I have seen severe network performance problems with:

  • Bad cabling. Really, try another one, properly shielded cat6. Bad, unshielded cables can take severe interference from any RF, especially of they lie around in loops
  • auto-negotiation mismatch between network interface and switch. When both sides try to agree on a common speed and fail, they may drop to half-duplex traffic which really hurts performance. Don't know about the timing though :-)
  • is any other user co-using you connection?
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The only cause I can imagine for this is interference with WiFi caused by you or a neighbor using some type of equipment that either uses or leaks microwaves. Try hard-wiring the system for one night.

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