It measures just under 6" by 4" and is under 2" in depth... weighs next to nothing and you'll hardly notice it on your desktop or by your TV. Connections are 3 USB, VGA, HDMI... !!! Ethernet [built in excellent wireless reception too] and SD. I use the HDMI to the DVI-D connection on my Samsung monitor and the high quality HD this machine outputs has transformed my viewing and monitor!

On board you have:
Windows® 8.1
' Intel® Baytrail(tm) T Quad Core Z3735F processor
' Intel® HD Graphics
' 2GB of DDR3L RAM
' 30GB total integrated storage
' 802.11 b/g/n Integrated Wireless Network
' 3X USB 2.0 ports
' HDMI & VGA input.

There is no fan and the Byte is totally quiet... you'll hear nothing. I'm not sure however if the hard drive is SSD... whatever it is, it's quiet and the Byte does not overheat.[Edit: just found out it's a Toshiba 30GB Disc Drive... though not SSD you're not aware of any drive at all!] After initial installation you'll probably be left with around 17 free GB.

On the back of the Byte where most connections are you have also the on/off switch, the DC 12v input and a headphone socket which you can also use of course to take to your sound system. Sound quality is top notch.

A few words about Windows 8.1... I am used to Windows 7 Home Premium which I've enjoyed using. I have a couple Nokia Lumia phones so using 8.1 on the Byte wasn't totally a new experience but I've found it equally a pleasure to use.

Back to the Byte... if you're looking for a really capable PC that plays 1080p HD video no problems and is well capable at general surfing I can highly recommend this little gem. I had the Byte up and running in no time... just added a wireless mouse and keyboard. If you need extra memory you have USB slots and the SD slot too. I'm just keeping mine fairly simple and don't intend to add much to the internal hard drive other than Media Player Classic. I have a wireless internet connection from router in the room above and normally I get about 12mB on my usual PC... the Byte receives 25mB on average through its aerial on the back.

To put it through its paces tonight I had a 1080p video playing alongside an SD video whilst surfing the net and processor use was still only around an average of 15%... RAM use averaged 56%. It's easy to quickly call up the task manager on 8.1 to check PC performance. No bloat ware on board.

It's very nippy around the internet and you can switch between standard desktop and Windows 8.1... with Windows 8.1 this really is a class act and is great to use and customise yourself. Start up time is fast... about 6 - 8 seconds and shut down is equally fast.

I'll update this review if needed but for the time being I can thoroughly recommend this cracking little machine. I had been checking out desktops at three times the price but the Byte has proved capable way beyond my expectations.

Edit/Update 19th August 2015
I took up the Microsoft offer of 'upgrading' to Windows 10 from 8.1 on the Quantum Byte. After trialling Windows 10 for a week I found the Byte was not as responsive as with 8.1. So I opted for the recovery mode back to 8.1, which I prefer anyway, and now everything is back to normal and the Byte is zapping around the internet once more with no sluggishness. Note that should you download Windows 10 you have just one month in which to make a decision after which you can't revert to 8.1 or Windows 7.

It has some form of solid state drive (not an actual removable SSD) and boots up very quickly, just a few seconds. Full Windows 8.1, and it looks like it has formatted down to 23GB, a couple more have then gone to Windows 8.1, so usable space left will need to be treated with care. There a slot for removable media, so you can easily expand this.

It has a Quad core processor, and feels very fast. It's even smaller than your average router, yet you can hide it away anywhere, or it's smart enough to keep on show, and would make a great HTPC or media server.All in all, I'm very impressed. But there are just two "buts" that I would warn about that loses it a star...

Firstly, and I believe others have commented, the wireless antennae (although pretty large) appears to do quite a poor job of holding and maintaining a good wireless signal. When I set the unit up, it was in the same room as the router, and it never dropped out once. But when it was moved to another room (not far away) I started to notice connection issues over wifi, dropping and coming back, slowdowns and latency, coming back again, or having to re-connect manually. I even used an upstairs wifi hotspot (very nearby!) and it didn't even want to lock onto that all that well. Given that these issues never happened in the same room as the router, and given that smartphones, tablets and laptops all never have a problem in all our rooms, I can only conclude that the wifi facility in this little box is not quite up to scratch. In the end, I decided to use a spare pair of Homeplug adaptors, and provide the unit with a proper "wired" Ethernet connection, and it immediately became rock solid, and all the wifi issues ceased. So for me, that's not a deal breaker, but a bit annoying, and what if I had not had a spare Homeplug? Just something to bear in mind...

The second disappointment, is that sound does not appear to carry through to TV with an HDMI cable. I use a very high quality HDMI cable (not that quality of cable will have anything to do with this issue), and guess what? no sound!!!Why not?I have another small PC I'm using as HTPC, and the sound goes straight from that box to the TV via HDMI. In the end, I had to use mini jack out from the headphone socket (at the same time as the HDMI) to get the sound out to the TV. This was a nuisance, because I had to find a line-level splitter, to make the sound go two ways, since various jacks were already being used, etc.

So to sum all this up - you will be delighted by looks, speed, boot up speed, quality, value for money, full copy of Windows 8.1, ease of set up etc etc - but you may likely have issues with sound over HDMI and patchy wifi performance.

Lastly, and I have seen this commented elsewhere, so I'm not the only one......why was my seal broken, with the writing on the seal "If this seal is broken, then product is used".I found inside, a shrunk-wrapped unit, and to me, it did [not] look used, and I felt I did have a new product. But the fact remains that for my purchase, and it would seem for some others - the seal has already been broken on arrival.

Other than that, I strongly recommend this machine.

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Update: 20th July 2015.

I've updated this to a 5-star rating, after contacting Qbyte support about the HDMI issue. It is totally possible to output sound from the Qbyte to TV over HDMI, but you may need to visit the Hardware and Sound, in Control Panel, and then make sure that default playback device is set correctly.

Here was the advice from support:

As for the HDMI, please make sure that the DEFAULT Playback device is set to HDMI.

Press both Windows Key + X
Select Control Panel *VIEW BY ::CATEGORY::*
Select Hardware and Sound
Select Sound
Verify HDMI is default output(Playback) device.

This then worked perfectly!

I expect to buy another of these, waiting until Windows 10 is out, rather than upgrading 8.1, so highly recommended.

I use this wired into my modem, with a bluetooth combined keyboard/trackpad, and an HDMI connection to a 42" smart TV. No problems so far - totally recommend it for "light" Home PC users orfor ultra-mobile workers. I used to use laptops, but now find this lovely bit of tech, combined with my tablet, works even better for me.

Bought for a friend who just needs a basic PC, but quickly realised how good it actually was. It works fine for his needs, internet browsing, XBMC for watching videos, no noticeable lag at all. I then did some testing and it also seems to work great for being a client using Steam to stream games from my main (wireless) PC. I'll now be buying myself 1 for the front-room to replace my HTPC as this does everything I need now that I can stream games.

Also, it's absolutely silent - perfect for not getting grief from the wife!

After that, it now fails to power on at all. It just flashes the front LED occasionally.

I've been trying to debug this via email with Quantum but there is little you can do apart from send it back - to Miami!!!!