2012 mac mini hanging at white screen on boot

My newish 2012 mini is hanging for ages (possibly indefinitely, certainly several minutes) at the white screen when starting up. There is no apple symbol, it does not respond to keyboard input such as holding shift for safe mode etc. it doesn't even get as far as powering up my FW800 external drive (although there is power to the USB bus as lights come on on other peripherals). The only thing I can do is power down again by holding the button.

I have heard this and similar issues referred to as 'the white screen of death' and the solution for some people seems to be PRAM resets or SMC resets. I managed to do a PRAM reset once, not sure how, I just got lucky and it responded to the keyboard. THis appeared to solve the problem, but now it's back and I can't reset the PRAM as it no longer responds to the keyboard. I'll try an SMC reset tonight.

Is there any way I can diagnose this, any kind of log that is produced? I tried starting in verbose mode but again no response to the keyboard. It's very disappointing as I spent a lot on the mini and I've already had black screens to contend with, now I've got white ones! Could it be another HD4000 bug? Is there a handshake process over DVI which could be stalling the mini?

Thanks for replies so far. I really don't want the hassle of returning to Apple if I can fix it myself, but obviously if it persists then that's the road I'll have to go down. My previous mac mini was far less issue-prone and I'm feeling pretty down on the whole purchase. If only Windows wasn't so awful I'd be very tempted to start speccing up a PC right now... (assuming I could get my money back from Apple!) and I've been Apple since Mac OS 7...

I'm hopeful that I can get it started after an SMC reset (or just at random since the problem seemed to be sporadic at first) and then try disk utility etc. I think I ran disk utility after the first occurence and it found no issues. It's a fusion drive though, so I'm worried it could fail in new and unusual ways! I have a full time machine backup so no risk of losing anything, just very annoying.

I'll unplug all USBs and replace my wireless mouse with a wired one to see if things improve.

Well... it's fixed at least for now but not sure how and no closer to understanding it. After leaving the computer on white screen all day, I came home to find that it had booted. So I ran disk utility, it didn't find anything but to be safe I booted into recovery and ran it again. After this the startup time was noticeably shorter than it had been prior to the issue - back to the near instant boot that the mini had when brand new. I haven't actually shut the mini down for any length of time since the 'fix' so the true test will be whether it boots up fine tomorrow...

Ah! It's not fixed after all! This morning it's back to the white screen of death... it's been that way for an hour so I've left it in the hope that it will get there eventually as it did yesterday. It seems to only be an issue after a full shutdown (i.e. not a restart). Will have to investigate further.

Post deleted

Thanks for the tips. I'll turn on verbose boot and hopefully then we'll start to get some useful data on the problem. I'm not looking forward to having to explain all this to an applecare rep over the phone (although perhaps the mention of verbose boot will get me put through to a techie) so hopefully I can solve this with your help...

Sir Ruben said:

This also happened to me, Mac would sit on a white screen for ages and then EVENTUALLY boot up, turned out to be me external Hdd which had stopped responding. Rebooted that and then the mac booted as normal.

Here's a vid I made of what I was experiencing:

http://www.youtube.com/watch?v=i8-zQiXtc0M&feature=plcp

Click to expand...

My only external HDD is my FW800 drive which I unplugged when the issue first occurred. I do have a few US devices which could be suspects... the mini has booted again now so time to start investigating.

So... after some testing, it appears to be some kind of USB related issue but I don't understand it. If I do a restart it's fine, if I do a shutdown then boot a minute later it's fine, if I leave it off for an hour then boot, it hangs. Even in verbose mode it doesn't get far enough to show anything. However, as soon as I unplugged my EyeTV USB it booted. Weird, but ultimately tolerable if it doesn't get worse. Will test further...

Resolved!

Okay, so it looks like the problem has been traced down to a faulty USB extension cable. This failed completely today so hopefully no more issues now it's gone.

Not resolved!

Ahhh!! It's still not over! Yesterday I was convinced that the USB extension cable I use to connect my EyeTV tuner was to blame. Evidence for this was:

Whenever I unplugged the cable and the device, the white screen instantly resolved. Plugging it back in later caused no problem.

After a few days, another problem emerged: the tuner couldn't be seen at all, it was as if it wasn't plugged in. Unplugging and replugging made no difference but a different extension cable instantly resolved the issue.

But this morning... white screen! Unplug USB, mini boots... replug USB... tuner vanished again!

Maybe the device itself has gone faulty. Problem is this only happens when the mini has been off for a while, so it is very hard to test.