I have three different unpowered 2.5" external hard drives--an old WD Passport, a Seagate FreeAgent Go, and a newer WD My Passport. All three have given me some combination of Event Log Warnings (Event ID 51), Event Log Errors (Event ID 11), and random disconnects. They can go for up to a few days without any problems, but eventually I will get Event Log entries or disconnections, especially during a full backup. I only use one of the drives at a time.
My first thought was that the drives are bad, but I have performed full tests on all of them from a different computer and they all passed.
The problem exists with or without the WD/Seagate software installed.
The problem exists regardless of what USB port I use, and with USB Selective Suspend on or off.
My computer came with a notoriously weak power supply, so I tried using the USB ports on my ViewSonic monitor--which is essentially a powered USB hub--but the problem didn't go away. (Is it safe to rule out the PSU then?)
Thinking it was a southbridge error, I got a PCI USB card but the problem still exists with the drive hooked up to those new ports. I guess it could still be the southbridge since that handles PCI too, but I have heard of people fixing their USB woes with a PCI card so I thought it was worth a shot.
I ran full Dell diagnostics from a bootable CD, and got no errors. There were "system board" and USB tests, but I don't know if it checked the southbridge specifically.
Can anyone think of anything else I can try to nail down the source of the problem? Non-HD USB devices (keyboard, mouse, printer) seem to work fine, although maybe they're just less sensitive to USB flakiness than a hard drive.
Any help would be greatly appreciated. Thanks in advance.