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Is it possible to have too many flash drives plugged in?

By Mugsy ยท 4 replies
Apr 4, 2012
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  1. I love my thumb-drives.

    I recently added a high-speed 8GB SanDisk USB Blade to my setup. I already have a slow old 64GB drive that I use just to backup my file archives, a 32GB OCZ Rally2 (that I've hidden from Windows because I have a full install of Linux on it that I can boot into), and another old 1GB that I've had for years.

    When I plugged the new Blade into my PC, my 120GB SSD boot drive "vanished" from my BIOS. When I unplugged the Blade, my SSD returned, I was sure that meant my new thumb-drive was bad. (I can plug all 5 drives in AFTER booting and the SSD is detected just fine, I just can't have them all plugged in BEFORE booting.)

    So I tried an experiment:

    I unplugged ALL of my thumb drives and plugged them back in one at a time, starting with the Blade. The SSD didn't "disappear" until after I plugged in my 5th thumb-drive. Tried different drives in different ports. It didn't matter. My SSD disappears from my BIOS with all 5 drives plugged in.

    I have two USB expansion ports on the front of my case, 4 more USB ports in a hub in a 3.5" bay, 6 USB devices plugged into the back of my PC including a 7-port hub with just one device plugged into it.

    I've never heard of something like this happening before. And USB-2.0 is "technically" capable of supporting 64 devices. So why is my PC barfing on one drive too many?

    Anyone else ever have a problem like this, where a USB flash drive "conflicts" with a SSD flash drive?
  2. Buckshot420

    Buckshot420 TS Enthusiast Posts: 301

    Try changing the drive letter under disk management. 2 drives are probably assigned the same drive letter resulting in neither showing up.
  3. Mugsy

    Mugsy TS Guru Topic Starter Posts: 389   +14

    As I noted in my question, the problem is not in Windows. It occurs at bootup/bios.
  4. Buckshot420

    Buckshot420 TS Enthusiast Posts: 301

    Is the HUB Bus powered or Self powered? Bus powered hubs that run strictly off USB could cause extremely slow R/W speeds and I could see that being so underpowered with all slots used that it could be the cause of other problems. Just a thought.
    Im not saying it has anything to do with your PSU, but each port can deliver .5A by specification. If you have a 7 port USB hub then the power supply should be at least 3.5A (7ports x .5A). So if you are using a Bus powered unit you can see the strain that is caused.
  5. Mugsy

    Mugsy TS Guru Topic Starter Posts: 389   +14

    USB flash drives and SSD conflict?

    The Thumb drives are plugged into a powered hub in the floppy bay. I have an unpowered 7 port hub as well with only my trackball and an RF receiver plugged into it.

    I've tried unplugging "other" devices, but it made no difference.

    I can boot just fine if I wait until AFTER BIOS detects my SSD before I plug in a fifth thumb drive, but my SSD (a 120GB Corsair GT) "vanishes" from BIOS if I plug all five drives in first. My HDD's... both IDE & Sata, are detected just fine. Only the SSD "disappears".

    Very odd. I've never heard of anything like this happening before.

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