Slow network on iMac 27"

Discussion in 'iMac' started by pihlopase, May 18, 2011.

  1. pihlopase macrumors newbie

    May 18, 2011
    Hello MacRumors forum users,
    Can anyone explain this?

    - Speedtest from the iMac9,1

    - Speedtest from the iMac11,1 (last year's i5 27" model I believe)

    Both machines are connected to the same switch, both have brand new Cat6, switches are brand new. Steps I have taken already

    - Deleted all network interfaces and recreated
    - Logged in to another account and tested
    - Tried just wireless
    - Tried just wired
    - Tried wireless and wired active at the same time
    - Tried Safari, Firefox, and Chrome
    - Made sure VPN was disabled

    I can't for the life of me figure this out. Both wired and wireless hover around 10-11Mpbs with any test. Every other networked device in the house, Boxee box, Wii, iPhone, PC, all blow the 27" iMac out of the water.

    Thanks in advance,
  2. mrfoof82 macrumors 6502a

    May 26, 2010
    Lawton, OK
    #2 is something that ISPs usually try to ensure they perform optimally on. Take its numbers with a grain of salt, *especially* if you have Comcast where PowerBoost can drastically alter your perceived performance.

    It's also external. This isn't testing your network. It's testing your connectivity to a host outside your network.

    Can you do some file transfers between computers in your home? That'll give you a better indication of your actual network's performance and bandwidth. For example, if you can sustain 300-400Mbps transferring files between computers on your network (which will saturate most SATA disks), getting only 10Mbps to is a separate unrelated issue.
  3. pihlopase thread starter macrumors newbie

    May 18, 2011
    First, I appreciate the response. I understand that is not a valid measure of network speed. I should have been more clear, and the title of this thread is most likely misleading. Previously I had done some simple network testing internally using iperf between the 27" iMac and a Debian box. No problems there:

    # iperf -c
    Client connecting to, TCP port 5001
    TCP window size: 129 KByte (default)
    [ 3] local port 64158 connected with port 5001
    [ ID] Interval Transfer Bandwidth
    [ 3] 0.0-10.0 sec 808 MBytes 677 Mbits/sec

    I should have been more clear and stated that using was the simplest way to visual traffic pulled down from the internet, and all that I was really concerned about. Poor performance is seen on any website, or torrent, or downloading an ISO, etc. My first thought was that this is related to DNS, but those settings are identical across all machines. I know it's something really simple I am missing here. I'm just blanking on it right now.
  4. pihlopase thread starter macrumors newbie

    May 18, 2011
    Just an update to this. Recently the drive in this box went bad. I reinstalled on a USB drive, and restored from backup, while I wait for a new drive. Good news is that the problems I described above have disappeared. Since I only restored my home directory I am thinking that this has something to do with a change made in some config file a while back. I try document any changes I make that might effect system performance, but it looks like this one slipped by me.

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