Intel iMac slow Wifi - G5 iMac fast

I just installed a brand new iMac (3GHz Intel). It's standing next to my old G5 iMac.
When I visit an Internet speedtester (speedtest.nl) the old G5 reports 230kbps every time (which it should). The new iMac however shows an enormous variation and seldom come above the 200kbps level.
The option-Airport click shows 130 as speed for the new iMac (I have a new Time Capsule connected to the Internet) and the G5 shows 54 as speed. That sounds okay to me.
I've deleted some Safari and Internet related plists and the first test in Safari did reach the 230kbps, but after that it dropped to about 80kbps. Firefox shows the same problems.
Anyone any idea how to tackle this problem?
Thx,
Marco

Remember there will be some contention between 802.11 G and 802.11 N. Just like when the G standard came out, there was an option to allow B compatibility. This means G clients had to RTC and CTS because the B clients could not talk above 11Mbits and therefore may or may not be able to grab a timeslot to transmit. Are you using 2.4G N or 5G N? You can tell when your iMac connects by holding down the option key and clicking the AirPort Icon. Just look at the channel you are on. Also look at the Rate. Anything above 54Mbits means you are using N. Channels 1 to 11 means you are on 2.4 and Channels that are higher means you are using A. Most likely you are on 2.4 since I am assuming all of your MACs are using the same WAP (wireless access point).
If you have both machines right next to each other, it can definitely be the coexistence between G and N networks. When you are using N with 2.4 you are using narrow band N with Apple products. This can be susceptible to interference. Try moving your machines away from each other and try it again.

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    com.apple.iokit.IODVDStorageFamily          1.7.1
    com.apple.iokit.IOCDStorageFamily          1.7.1
    com.apple.iokit.IOAHCISerialATAPI          2.6.1
    com.apple.driver.AppleThunderboltDPOutAdapter          3.1.7
    com.apple.driver.AppleThunderboltDPInAdapter          3.1.7
    com.apple.driver.AppleThunderboltDPAdapterFamily          3.1.7
    com.apple.driver.AppleThunderboltPCIDownAdapter          1.4.5
    com.apple.iokit.IOSCSIBlockCommandsDevice          3.6.6
    com.apple.iokit.IOUSBMassStorageClass          3.6.0
    com.apple.iokit.IOSCSIArchitectureModelFamily          3.6.6
    com.apple.iokit.IOUSBHIDDriver          660.4.0
    com.apple.driver.AppleUSBMergeNub          650.4.0
    com.apple.driver.AppleUSBComposite          656.4.1
    com.apple.iokit.IOUSBUserClient          660.4.2
    com.apple.driver.AppleThunderboltNHI          2.0.1
    com.apple.iokit.IOThunderboltFamily          3.2.7
    com.apple.iokit.IOEthernetAVBController          1.0.3b4
    com.apple.driver.mDNSOffloadUserClient          1.0.1b5
    com.apple.iokit.IO80211Family          630.35
    com.apple.iokit.IONetworkingFamily          3.2
    com.apple.iokit.IOFireWireFamily          4.5.5
    com.apple.iokit.IOAHCIFamily          2.6.5
    com.apple.iokit.IOUSBFamily          675.4.0
    com.apple.driver.AppleEFINVRAM          2.0
    com.apple.iokit.IOHIDFamily          2.0.0
    com.apple.driver.AppleEFIRuntime          2.0
    com.apple.iokit.IOSMBusFamily          1.1
    com.apple.security.sandbox          278.11
    com.apple.kext.AppleMatch          1.0.0d1
    com.apple.security.TMSafetyNet          7
    com.apple.driver.AppleKeyStore          2
    com.apple.driver.DiskImages          371.1
    com.apple.iokit.IOStorageFamily          1.9
    com.apple.iokit.IOReportFamily          23
    com.apple.driver.AppleFDEKeyStore          28.30
    com.apple.driver.AppleACPIPlatform          2.0
    com.apple.iokit.IOPCIFamily          2.9
    com.apple.iokit.IOACPIFamily          1.4
    com.apple.kec.corecrypto          1.0
    com.apple.kec.pthread          1
    System Profile:
    Model: iMac12,2, BootROM IM121.0047.B1F, 4 processors, Intel Core i7, 3.4 GHz, 12 GB, SMC 1.72f1
    Graphics: AMD Radeon HD 6970M, AMD Radeon HD 6970M, PCIe, 2048 MB
    Memory Module: BANK 0/DIMM0, 2 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353637334648302D4348392020
    Memory Module: BANK 1/DIMM0, 4 GB, DDR3, 1333 MHz, 0x0000, 0x000000000000000000000000000000000000
    Memory Module: BANK 0/DIMM1, 2 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353637334648302D4348392020
    Memory Module: BANK 1/DIMM1, 4 GB, DDR3, 1333 MHz, 0x0000, 0x000000000000000000000000000000000000
    AirPort: spairport_wireless_card_type_airport_extreme (0x168C, 0x9A), Atheros 9380: 4.0.74.0-P2P
    Bluetooth: Version 4.2.3f10 13477, 3 services, 23 devices, 1 incoming serial ports
    Network Service: Wi-Fi, AirPort, en1
    Serial ATA Device: WDC WD1001FALS-403AA0, 1 TB
    Serial ATA Device: OPTIARC DVD RW AD-5690H
    USB Device: FaceTime HD Camera (Built-in)
    USB Device: Hub
    USB Device: Backup+ SL
    USB Device: BRCM2046 Hub
    USB Device: Bluetooth USB Host Controller
    USB Device: Hub
    USB Device: IR Receiver
    USB Device: Internal Memory Card Reader
    Thunderbolt Bus: iMac, Apple Inc., 22.1
    Model: iMac12,2, BootROM IM121.0047.B1F, 4 processors, Intel Core i7, 3.4 GHz, 12 GB, SMC 1.72f1
    Graphics: AMD Radeon HD 6970M, AMD Radeon HD 6970M, PCIe, 2048 MB
    Memory Module: BANK 0/DIMM0, 2 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353637334648302D4348392020
    Memory Module: BANK 1/DIMM0, 4 GB, DDR3, 1333 MHz, 0x0000, 0x000000000000000000000000000000000000
    Memory Module: BANK 0/DIMM1, 2 GB, DDR3, 1333 MHz, 0x80CE, 0x4D34373142353637334648302D4348392020
    Memory Module: BANK 1/DIMM1, 4 GB, DDR3, 1333 MHz, 0x0000, 0x000000000000000000000000000000000000
    AirPort: spairport_wireless_card_type_airport_extreme (0x168C, 0x9A), Atheros 9380: 4.0.74.0-P2P
    Bluetooth: Version 4.2.3f10 13477, 3 services, 23 devices, 1 incoming serial ports
    Network Service: Wi-Fi, AirPort, en1
    Serial ATA Device: WDC WD1001FALS-403AA0, 1 TB
    Serial ATA Device: OPTIARC DVD RW AD-5690H
    USB Device: FaceTime HD Camera (Built-in)
    USB Device: Hub
    USB Device: Backup+ SL
    USB Device: BRCM2046 Hub
    USB Device: Bluetooth USB Host Controller
    USB Device: Hub
    USB Device: IR Receiver
    USB Device: Internal Memory Card Reader
    Thunderbolt Bus: iMac, Apple Inc., 22.1
    I use my iMac daily for work and it happens from 4-10 times a day depending on what applications i'm using. More if I'm trying to render a video. It is really furstrating and keeps me from doing any work at all, I can't keep working like this but I have no choise. I really can't be without my computer for very long as I use it to do everything and I do not have another. Also I have all my files on the hard drive. I have bought a Seagate external HD to back up my files onto so I can make a genus bar appointment but everytime I run time machine or try to copy any of my files over to the external HD the machine restarts and disrupts the file transfer. So I can't even back up my files which are really important to me. I even had to retype this whole message becuase my imac restarted while I was fulling in this question.
    What is worse is that I bought the extra warrenty (Apple Care) which is due to expire sometime in March 2014 I'm unsure of the date. Might have expired already I don't know. So I need to get this fixed ASAP.
    Extra information on the machine:
    iMac
    27-inch, Mid 2011
    Processor  3.4 GHz Intel Core i7
    Memory  12 GB 1333 MHz DDR3
    Graphics  AMD Radeon HD 6970M 2048 MB
    Software  OS X 10.9.2 (13C64)
    Can anyone see from the information I have given about what could be wrong with my machine?
    Any help or assistance would be much appriciated.
    Thanks,
    James

    Hi.  I am currently having the same issue on my 2011 27"  3.1 GHz i5  with 12 GB 1333 MHz DDR3
    For the last couple of months I have been experiencing random restarts, power offs and so on.  I have already had this escalated and had my machine taken into Apple to run a Hardware test.  They redid the newest OSX version in store and ran the AHT for an hour and got no results.  The Genius Bar were asked by Apple Canada to run an all night test.  According to Apple they ran the test for 4 hours and got nothing.  I was then told to take the machine home and run it with just the memory that was original in the machine.  I stressed tested the video card with a benchmark tool called Heaven for 2 hours.  90C was the temp and no failure.  I did a Terminal "Yes" loop for a couple of hours and no failure on the CPU.  I ran the Apple Hardware Test for 11 minutes and this is the result.
    I also have a video of what happened after I restarted the test after about a 5 minute cooldown period.  20 minutes into the test the Imac stalled and made 3 long beeps over and over again like an alarm with a long pause between.  I took the memory out of the DIMM 0 & 1 slots and replaced them in the 2&3 slots rand the test and got nothing after 2 hours.  I put the memory back in the original spot and ran it again and got no results.  Apple contacted the "Genius" techs and they informed them that I had fixed the problem and everything should be good now.  I was also told to go ahead and transfer back over my Time Machine Backup.  Since this all happened I have had the Imac restart 2 times in the last almost 2 weeks and today got this error message
    Thu Mar 20 13:25:18 2014
    panic(cpu 1 caller 0xffffff80226dbe2e): Kernel trap at 0xffffff80228b3b40, type 13=general protection, registers:
    CR0: 0x000000008001003b, CR2: 0x0000000107b81000, CR3: 0x0000000025449000, CR4: 0x00000000000606e0
    RAX: 0xffffff803f364ab0, RBX: 0x00000000000063e0, RCX: 0xffffff8022c50100, RDX: 0x0000000000006300
    RSP: 0xffffff81842e3a60, RBP: 0xffffff81842e3aa0, RSI: 0xffffff803db9af08, RDI: 0x000000000000000f
    R8:  0x0000000000000804, R9:  0x0000000000000001, R10: 0x00000000000003ff, R11: 0xffffffffffffffff
    R12: 0x000000000501a8c0, R13: 0xffffff8022cf2840, R14: 0xdeadbeefdeadbeef, R15: 0x0000000000000804
    RFL: 0x0000000000010282, RIP: 0xffffff80228b3b40, CS:  0x0000000000000008, SS:  0x0000000000000010
    Fault CR2: 0x0000000107b81000, Error code: 0x0000000000000000, Fault CPU: 0x1
    Backtrace (CPU 1), Frame : Return Address
    0xffffff817b495df0 : 0xffffff8022622fa9
    0xffffff817b495e70 : 0xffffff80226dbe2e
    0xffffff817b496040 : 0xffffff80226f3326
    0xffffff817b496060 : 0xffffff80228b3b40
    0xffffff81842e3aa0 : 0xffffff80228e7a44
    0xffffff81842e3c00 : 0xffffff80228c88c6
    0xffffff81842e3c50 : 0xffffff80228c8bc2
    0xffffff81842e3e30 : 0xffffff80228b6d2d
    0xffffff81842e3e50 : 0xffffff8022852763
    0xffffff81842e3e80 : 0xffffff8022834f83
    0xffffff81842e3ea0 : 0xffffff802282b20c
    0xffffff81842e3f50 : 0xffffff802283207c
    0xffffff81842e3fb0 : 0xffffff80226d6ff7
    BSD process name corresponding to current thread: kernel_task
    Mac OS version:
    13C64
    Kernel version:
    Darwin Kernel Version 13.1.0: Thu Jan 16 19:40:37 PST 2014; root:xnu-2422.90.20~2/RELEASE_X86_64
    Kernel UUID: 9FEA8EDC-B629-3ED2-A1A3-6521A1885953
    Kernel slide:     0x0000000022400000
    Kernel text base: 0xffffff8022600000
    System model name: iMac12,2 (Mac-942B59F58194171B)
    System uptime in nanoseconds: 44509557372694
    last loaded kext at 43534719525427: com.apple.driver.AppleIntelMCEReporter 104 (addr 0xffffff7fa4e64000, size 49152)
    last unloaded kext at 43747598346449: com.apple.driver.AppleIntelMCEReporter 104 (addr 0xffffff7fa4e64000, size 32768)
    loaded kexts:
    com.maudio.usb.fasttrackpro.driver 1.9.4
    com.avast.AvastFileShield 2.1.0
    com.avast.PacketForwarder 1.4
    com.jft.driver.PdaNetDrv 1.0.64
    com.orderedbytes.driver.ControllerMateFamily 4.4.3
    com.orderedbytes.driver.CMUSBDevices 4.4.3
    com.apple.filesystems.afpfs 11.1
    com.apple.nke.asp-tcp 8.0.1
    com.apple.driver.AppleBluetoothMultitouch 80.14
    com.apple.driver.AppleHWSensor 1.9.5d0
    com.apple.iokit.IOBluetoothSerialManager 4.2.3f10
    com.apple.iokit.IOUserEthernet 1.0.0d1
    com.apple.Dont_Steal_Mac_OS_X 7.0.0
    com.apple.driver.AGPM 100.14.15
    com.apple.driver.AppleHWAccess 1
    com.apple.filesystems.autofs 3.0
    com.apple.driver.AudioAUUC 1.60
    com.apple.driver.AppleMikeyHIDDriver 124
    com.apple.driver.AppleHDA 2.6.0f1
    com.apple.driver.AppleUpstreamUserClient 3.5.13
    com.apple.kext.AMDFramebuffer 1.2.0
    com.apple.driver.ACPI_SMC_PlatformPlugin 1.0.0
    com.apple.AMDRadeonX3000 1.2.0
    com.apple.driver.AppleThunderboltIP 1.1.2
    com.apple.kext.AMD6000Controller 1.2.0
    com.apple.driver.AppleMikeyDriver 2.6.0f1
    com.apple.driver.AppleBacklight 170.3.5
    com.apple.driver.AppleMCCSControl 1.1.12
    com.apple.driver.AppleIntelHD3000Graphics 8.2.4
    com.apple.driver.AppleSMCPDRC 1.0.0
    com.apple.iokit.BroadcomBluetoothHostControllerUSBTransport 4.2.3f10
    com.apple.driver.AppleSMCLMU 2.0.4d1
    com.apple.driver.AppleLPC 1.7.0
    com.apple.driver.AppleIntelSNBGraphicsFB 8.2.4
    com.apple.iokit.SCSITaskUserClient 3.6.6
    com.apple.driver.AppleUSBCardReader 3.4.1
    com.apple.driver.AppleIRController 325.7
    com.apple.AppleFSCompression.AppleFSCompressionTypeDataless 1.0.0d1
    com.apple.AppleFSCompression.AppleFSCompressionTypeZlib 1.0.0d1
    com.apple.BootCache 35
    com.apple.driver.XsanFilter 404
    com.apple.iokit.IOAHCIBlockStorage 2.5.1
    com.apple.driver.AppleUSBHub 666.4.0
    com.apple.driver.AppleFWOHCI 4.9.9
    com.apple.driver.AirPort.Atheros40 700.74.5
    com.apple.iokit.AppleBCM5701Ethernet 3.8.1b2
    com.apple.driver.AppleAHCIPort 3.0.0
    com.apple.driver.AppleUSBEHCI 660.4.0
    com.apple.driver.AppleRTC 2.0
    com.apple.driver.AppleACPIButtons 2.0
    com.apple.driver.AppleHPET 1.8
    com.apple.driver.AppleSMBIOS 2.1
    com.apple.driver.AppleACPIEC 2.0
    com.apple.driver.AppleAPIC 1.7
    com.apple.driver.AppleIntelCPUPowerManagementClient 216.0.0
    com.apple.nke.applicationfirewall 153
    com.apple.security.quarantine 3
    com.apple.driver.AppleIntelCPUPowerManagement 216.0.0
    com.apple.security.SecureRemotePassword 1.0
    com.apple.driver.AppleMultitouchDriver 245.13
    com.apple.driver.AppleBluetoothHIDKeyboard 170.15
    com.apple.driver.IOBluetoothHIDDriver 4.2.3f10
    com.apple.driver.AppleHIDKeyboard 170.15
    com.apple.iokit.IOSerialFamily 10.0.7
    com.apple.iokit.IOSurface 91
    com.apple.iokit.IOBluetoothFamily 4.2.3f10
    com.apple.kext.triggers 1.0
    com.apple.driver.DspFuncLib 2.6.0f1
    com.apple.vecLib.kext 1.0.0
    com.apple.driver.IOPlatformPluginLegacy 1.0.0
    com.apple.iokit.IOAcceleratorFamily 98.14
    com.apple.driver.AppleThunderboltEDMSink 2.1.3
    com.apple.kext.AMDSupport 1.2.0
    com.apple.AppleGraphicsDeviceControl 3.4.35
    com.apple.iokit.IOFireWireIP 2.2.6
    com.apple.driver.AppleHDAController 2.6.0f1
    com.apple.iokit.IOHDAFamily 2.6.0f1
    com.apple.driver.AppleBacklightExpert 1.0.4
    com.apple.driver.AppleSMBusController 1.0.11d1
    com.apple.iokit.IONDRVSupport 2.4.1
    com.apple.iokit.IOBluetoothHostControllerUSBTransport 4.2.3f10
    com.apple.driver.AppleUSBAudio 2.9.5f4
    com.apple.iokit.IOAudioFamily 1.9.5fc2
    com.apple.kext.OSvKernDSPLib 1.14
    com.apple.driver.AppleSMC 3.1.8
    com.apple.driver.AppleSMBusPCI 1.0.12d1
    com.apple.driver.IOPlatformPluginFamily 5.7.0d10
    com.apple.iokit.IOGraphicsFamily 2.4.1
    com.apple.iokit.IOSCSIMultimediaCommandsDevice 3.6.6
    com.apple.iokit.IOBDStorageFamily 1.7
    com.apple.iokit.IODVDStorageFamily 1.7.1
    com.apple.iokit.IOCDStorageFamily 1.7.1
    com.apple.iokit.IOAHCISerialATAPI 2.6.1
    com.apple.driver.AppleThunderboltDPInAdapter 3.1.7
    com.apple.driver.AppleThunderboltDPOutAdapter 3.1.7
    com.apple.driver.AppleThunderboltDPAdapterFamily 3.1.7
    com.apple.driver.AppleThunderboltPCIDownAdapter 1.4.5
    com.apple.iokit.IOSCSIBlockCommandsDevice 3.6.6
    com.apple.iokit.IOUSBMassStorageClass 3.6.0
    com.apple.iokit.IOSCSIArchitectureModelFamily 3.6.6
    com.apple.iokit.IOUSBHIDDriver 660.4.0
    com.apple.driver.AppleUSBMergeNub 650.4.0
    com.apple.driver.AppleUSBComposite 656.4.1
    com.apple.iokit.IOUSBUserClient 660.4.2
    com.apple.driver.AppleThunderboltNHI 2.0.1
    com.apple.iokit.IOThunderboltFamily 3.2.7
    com.apple.iokit.IOFireWireFamily 4.5.5
    com.apple.iokit.IO80211Family 630.35
    com.apple.iokit.IOEthernetAVBController 1.0.3b4
    com.apple.driver.mDNSOffloadUserClient 1.0.1b5
    com.apple.iokit.IONetworkingFamily 3.2
    com.apple.iokit.IOAHCIFamily 2.6.5
    com.apple.iokit.IOUSBFamily 675.4.0
    com.apple.driver.AppleEFINVRAM 2.0
    com.apple.driver.AppleEFIRuntime 2.0
    com.apple.iokit.IOHIDFamily 2.0.0
    com.apple.iokit.IOSMBusFamily 1.1
    com.apple.security.sandbox 278.11
    com.apple.kext.AppleMatch 1.0.0d1
    com.apple.security.TMSafetyNet 7
    com.apple.driver.AppleKeyStore 2
    com.apple.driver.DiskImages 371.1
    com.apple.iokit.IOStorageFamily 1.9
    com.apple.iokit.IOReportFamily 23
    com.apple.driver.AppleFDEKeyStore 28.30
    com.apple.driver.AppleACPIPlatform 2.0
    com.apple.iokit.IOPCIFamily 2.9
    com.apple.iokit.IOACPIFamily 1.4
    com.apple.kec.corecrypto 1.0
    com.apple.kec.pthread 1
    Model: iMac12,2, BootROM IM121.0047.B1F, 4 processors, Intel Core i5, 3.1 GHz, 12 GB, SMC 1.72f1
    Graphics: AMD Radeon HD 6970M, AMD Radeon HD 6970M, PCIe, 1024 MB
    Memory Module: BANK 0/DIMM0, 2 GB, DDR3, 1333 MHz, 0x02FE, 0x45424A3231554538424655302D444A2D4620
    Memory Module: BANK 1/DIMM0, 2 GB, DDR3, 1333 MHz, 0x02FE, 0x45424A3231554538424655302D444A2D4620
    Memory Module: BANK 0/DIMM1, 4 GB, DDR3, 1333 MHz, 0x0198, 0x393930353432382D3034332E4130304C4620
    Memory Module: BANK 1/DIMM1, 4 GB, DDR3, 1333 MHz, 0x0198, 0x393930353432382D3034332E4130304C4620
    AirPort: spairport_wireless_card_type_airport_extreme (0x168C, 0x9A), Atheros 9380: 4.0.74.0-P2P
    Bluetooth: Version 4.2.3f10 13477, 3 services, 23 devices, 1 incoming serial ports
    Network Service: AirPort, AirPort, en1
    Network Service: Bluetooth PAN, Ethernet, en2
    Serial ATA Device: ST31000528AS, 1 TB
    Serial ATA Device: HL-DT-STDVDRW  GA32N
    USB Device: Hub
    USB Device: FastTrack Pro
    USB Device: USB2.0 Hub
    USB Device: Internal Memory Card Reader
    USB Device: IR Receiver
    USB Device: Hub
    USB Device: USB Axiom 61
    USB Device: BRCM2046 Hub
    USB Device: Bluetooth USB Host Controller
    USB Device: FaceTime HD Camera (Built-in)
    Thunderbolt Bus: iMac, Apple Inc., 22.1
    I would also like to add that The Second High Level tech I spoke to told me to use a program to take an image of what my computer was doing when the fresh install of Mavericks was installed and then again after the Time Machine restore.  I sent both and have had no response back. The "Engineers of Apple" would be taking a look at those files. This is what I was told anyway's.
    So I would like any advise because Apple hasn't been too helpful.  I haven't heard anything back at all. Its been a little while.  This seems that it could be an issue. I sat in the store speaking to a gentleman with a brand new iMac 27 inch that was having the same exact issues.  I was told his was newer so they were not the same.  The owner of the new iMac just rolled his eyes and laughed. James McConville seems to be having the same issue and I have read quite a few others before I saw this post from yesterday.
    Help Us Please. 

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