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I've got 3 hard drives (with power supply, USB 2.0 and 3.0). They are all recognized by Windows7 x64 when they're plugged in individually, or when 2 of them are plugged in at the same time (on any of my 4 laptop's USB ports).

However, when the 3 of them are plugged in at the same, W7 only detects the 2 first ones plugged in.

I also tried to plug them on a hub (which has a power supply) and it gives the same result.

When the 3 of them are plugged in at the same time and there's 1 or more pen drives plugged in, only 2 hard drives are recognized but all the pen drives are recognized as well...

Anyone might have a clue why that's happening?

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migrated from Jan 12 '12 at 1:56

This question came from our site for professional and enthusiast programmers.

this is more of a super user question. but i would guess that the third is underpowered. – madmik3 Jan 12 '12 at 1:17
All three are powered? – Paul Jan 12 '12 at 2:30
definitely not power supply, it was just an "a signature collision with another disk": other usefull link… – user1144446 Jan 12 '12 at 22:49
up vote 1 down vote accepted

1) This question would definitely have been better on Live and learn :)

2) This link has two good suggestions:

a) power supply

 ... and/or ...

b) Manually enable the (third) drive in Disk Mgr (where it might be visible, to enable)

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