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110931
June 12th, 2014 11:00
Latitude e6540 USB connect and disconnect randomly
I have a latitude E6540 and when I connect a external usb 3.0 disk it begins connect and disconnect randomly. I have tryed another disk and I have the same problem. This USB disk in other latitude E6540 works fine. I have disabled power option in the usb devices and reinstall drivers but nothing solved the problem. windows 7 x64 Thanks Fernando
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Darrellspeed
2 Posts
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September 29th, 2015 02:00
Hi i have a 6420, and it is also disconnecting the usb drives. please can you advise.
Mr.Ric
1 Message
2
June 28th, 2016 11:00
Everyone,
I have the solution to our problem. I have been dealing with this same issue for a while now. I have a Seagate "Samsung Spinpoint ST2000LM003 2TB 5400 RPM 32 MB SATA 6.0Gb/s 2.5" Internal Notebook HD" that was in a Seagate case.
I have been working with Dell for a while. The have replaced my Docking station. They have replaced my motherboard. All attempts seem to work for a short time, but the random connect/disconnect keeps coming back.
I took the drive out of the Seagate case, as I thought maybe it had a SATA to USB3.0 board problem and bought a Inateck USB3.0 (SATA I, II, III HD/SSD) case. I put the drive in it and still have the same problem. I have other external drives (smaller in size) that do not do this.
Today I took the 2TB out and used my "CoolGear" USB 3.0 Drive Adapter (handles EIDE/SATA of ALL sizes and is externally powered [12V @ 4.0A]. I'm not having any connection problems !
What I have learned: The 2TB drive is +5V @ 850mA. USB 3.0 specification is supposed to be 900mA per port. The E6540 reports 500mA per port everywhere in Device Manager. My smaller drives are indeed less than or closser to 500mA (the 500GB is 451mA, the 1TB I can't verify but I'm sure it's just over 500mA). What is being reported in Device Manager is CORRECT. Somehow, Dell has a design flaw in the E6540 boards that is underpowering the USB 3.0 ports.
Your drives will work if you use a self powered USB 3.0 hub that truly supports the 900mA per port that the USB 3.0 specifications call for. The Dell ports will do the high speed comms, just not the power.
I'm saddened that I have to report this, but it needs to be said.