Saturday, January 4, 2014

Mac Mini Goes to Sleep, Won’t Wake Up: The Problem and the Solution

A few months ago, I looked at the Geekbench performance ratings for my various Macs.  I had two old Mac Pro towers, which I had at my office as well as my home.  These were huge, indestructible machines.  But they were getting old at 7 years old, and their power consumption was very high. 

I noticed that one model of Mac Mini (late 2012, Intel Core i7-3720QM 2.6Ghz (4 cores), had a Geekbench rating of 11678.  This was much higher than the rating of my old Mac Pro, which was 4023.  It was one of the 10 fastest machines at that time (mid-2013) but was hard to find.  It is still hard to find for some reason. 

As a comparison, the Geekbench rating for a far more expensive Mac Pro (mid 2012, 12 Gb RAM, 12-Core 2.4GHz Intel Xeon Processor, 1 Tb drive, $3529 at B&H Photo in July 2013) is 17642.  My MacBook Pro (late 2011, 2.2 Ghz i7 processors) has a Geekbench rating of 9281. 

I bought one of these Mac Mini machines from B & H Photo in New York for $899.  It had, among other things, an HDMI output and USB3.0 ports.  I was particularly interested in upgrading all my Macs to USB3.0 because it was so much faster than USB2.0; and so many external hard drives from Seagate and Western Digital were now available with USB3.0.  The Mac Mini came with a 1Tb 5400rpm hard drive, and I put in a 512Gb Samsung 840 Series Solid State Drive (SSD).  Putting an SSD drive in your computer instantly transforms it into an awesomely fast machine, blazingly fast especially when starting up. 

I’ve been very happy with this new machine.  My old Mac Pros weighed over 50 pounds, and the new Mac Mini weighs about 2 pounds.  I can carry it back and forth from the office to my summer home.  It is pretty dang fast and a great replacement for my Mac Pros, which I used as a hub for all my Aperture libraries – still photos and videos which are stored in external hard drives (which are housed in external 4-bay RAID enclosures or with OWC Voyager docks). 

I had almost no problems with this setup.  I connected all my USB drives and other USB accessories with an Anker 4-port USB hub.  This hub came with a charger, and it worked perfectly.  I had absolutely no problems.  However, I needed more USB ports.  I bought a
HooToo HT-UH008 USB 3.0 Hub (7 Port, Bus-Powered, Detachable 2ft USB Data Cable & 2.3ft Charging Cable, Strip-Shaped Design) from Amazon.  This hub did not come with a power adapter.  I did know that the more USB devices you have on a hub, the more power you need.  I therefore unearthed an old charger for a cell phone and attached a USB cord with a power tip on the end, and plugged that into the Hootoo hub. 

The Hootoo hub worked well, but I started noticing that if the Mac Mini ever went to sleep, it was absolutely impossible to wake up.  I did the usual things, like resetting PRAM and the SMC controller.  Nothing worked.  Pulling out the USB hub did not work.  The only thing I could do, if the computer went to sleep and then into a coma, was to pull out the power cord from the Mac Mini and restart. 

I did more reading on forums, and a few forums gave me the solution to my problem.  The problem is that a USB hub connected to a Mac requires a lot of power.  If that USB hub does not have enough power, then for some reason the Mac that the USB hub is connected to will go into a coma.  It simply will not wake up from Sleep. 

My older Anker 4-port hub came with a power supply that is rated to output 2.5 amps.  I connected an old Apple ipad charger, which supplies 3.0 amps, and the Mac Mini is now waking up from sleep just fine – and super quickly.  I think that the problem is solved.  I can also see that there is a Hootoo hub on Amazon now that sells with a 4-amp charger.  The older Hootoo hub that I bought, and which did not come with a charger, is discontinued. 

Summary: If you are having problems waking up your Mac or PC from its sleep state, then see if the problem is being caused by your USB hub.  If taking the USB hub off your laptop solves the problem, then look into providing more power to your USB hub. 

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