Instruction: Answer the given question by extracting information from the supporting document.

Input:
Question: Is it fully compatible with Windows 8.1 or will my PC crash ?
Document: The product is solid and works the way it advertised. It works great both on my Mac Air (2012) and my Windows 7 & 8 PC as well. The build quality is solid and the logo on top of the unit pulses in red glow when the unit is active.
Worked great on all computers.Tried on both PC and Mac with (Windows Vista, 7, and Mac OS 10.5, 10.7, as well as the 10.8).Also worked great on both USB 2.0 & 3.0 ports,Great product. Just wish it would be a bit less expensive.
Did I mention this was fast? I have a 64GB SD card in my Windows Phone and connected to my PC it takes about 6.5 hours to copy my 54GB library over. Using this device on a USB 3.0 port the same copy time to ~2.1 hours!
Giving this 5 stars because It's fast, looks good, and does what it is supposed to do very well. I bought this to import images from my DSLR camera since the files are very large. The photos import extremely fast when plugged into a USB 3.0 port. The 'Kingston' logo lights up when a card is plugged in but it's not that bright or distracting. I have used this with Windows 7, 8 & 8.1 with no problems whatsoever.
Great product. Easy installation in Win7. Comes with 3.0 connector, backward compatible with 2.0. Solid construction. 1 drawback, no USB slot.
Using this with a hackintosh, 10.6.8. Disk Speed Test (Black magic design) reports the following with a 1GB testSanDisk Extreme Pro DSHC UHS-1 Card (rated up to 95MB/s)USB 2.0 port: 27 MB/s write, 37.4 MB/s readUSB 3.0 port: 63.7 MB/s write, 79.2 MB/s readNice.
From the start, I have to say I quite like the design of this reader that prompt my order.Upon using it, I hope I didn't receive a lemon.Using it to read my Kington SD-HC 4GB and a 4GB MicroSD on my computer's USB 3.0 port running on Window 8.1 pro is such a big disappointment.The connection kept on going off that told me that the hardware could not be found and then reconnects again automatically, but the file copying process had stopped.
Update 6/9/13: The replacement unit died this morning. I sat down at my computer to clear a few memory cards and the light on the top won't light up. I tried unplugging the cable at both ends and re-booting the PC. Neither worked. Needless to say i will be contacting Scott from Kingston (see below). Lowering this item to 1 star. Needless to say any replacement from Kingston will hopefully be a superior model or a full refund.
These are great. Windows 8? Doesn't work.
This card reader requires a firmware update if you want to use this with windows 7 and windows 8.  google: (FCR-HS3 USB 3.0 Media Reader &#8212; Firmware Upgrade).
Answer: It works just fine on both.  Have connected it to Vista, 7 and 8 without issue.  But when a card is in it, the light glows like the sun.