T400 can't boot from USB hard drive?

i have a hard drive with a perfectly bootable operating system installed on it. if i use the hard drive as an internal hard drive, it boots perfectly. but when i put it in an enclosure and then attach it using a usb cable, my t400 won't boot from it. i don't think this is at all a software problem because the drive boots just fine when it's not in the enclosure. i also ruled out the possibility that there's a physical problem with the cable, enclosure, or hard drive because the drive is recognized and works perfectly if i use it as an external.

i've already put "-usb hdd" on the list of devices to boot from. it's placed above my internal hard drive but still doesn't work. if i try to choose the usb hard drive manually from a list of all available devices i can boot from, the usb hard drive doesn't appear on the list. i googled a thread that claims the "-" means the hard drive is not recognized:

http://www.thinkpads.com/forum/viewtopic.php?f=18&t=74994

i changed usb cables, and even watched to make sure the light on the enclosure turned on when the computer is powered on. sometimes it's on, sometimes it's off but it makes no difference. either way, i can't boot from it. i can't turn that "-" into a "+", which is what some people in that thread were able to do. i've tried shutting off before plugging in the drive and restarting the computer with the drive already plugged in. still nothing.

i have the latest version of the bios available from lenovo already. is the t400 simply incapable of booting from a usb hard drive, or have i overlooked something?

 

I had the same problem in the last few days with my X220. Booting from a hard drive using a usb/sata cable or AC powered enclosure results in a BSOD in the middle of the Win 7 splash screen. Happened with an Intel and Samsung ssd that both boot fine if installed in the hard drive bay.

 

Windows does not support booting from a USB drive unless the OS is modified. When windows loads it polls devices and then disconnects the USB devices temporally to load the real driver that Windows uses for USB. This causes a BSOD. It's like booting from a HD internally then yanking it and reconnecting it really fast.

The modified versions will keep USB connections alive during this boot process which will not cause BSOD

EDIT: [Tutorial] Boot and run Windows 7 from USB hard disk by Marietto2009 - reboot.pro

if you are still interested in booting Windows from a USB Hard Drive/Flash Drive

 

vinuneuro's problem is not the same as mine. My problem precedes the operating system. I can't get my T400 to even recognize the existence of my USB hard drive. Anyone have any ideas on how to solve that?

 

depending on how old the drive is, it may require more power than what the USB port can supply.

 

i don't know how you knew this, but you were absolutely right. thanks a lot.

 

vinuneuro: Windows doesn't handle switching hard drive controllers very well. That is most likely the cause of the blue screens.

 

Thanks ha1o and bogatyr, that seems like a painfully archaic limitation considering it's 2012.

Glad casualattire found the solution to his issue.