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

Mugsy

Posts: 772   +203
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?
 
Try changing the drive letter under disk management. 2 drives are probably assigned the same drive letter resulting in neither showing up.
 
Try changing the drive letter under disk management. 2 drives are probably assigned the same drive letter resulting in neither showing up.
As I noted in my question, the problem is not in Windows. It occurs at bootup/bios.
 
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.
 
USB flash drives and SSD conflict?

Is the HUB Bus powered or Self powered?
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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