I have the same problem with my Shuttle SB61G2V3 here in Japan (I'm from Australia by the way). I hope the information below can be of help to someone with a similar problem.
About one year ago, just after the 1-year warranty expired here, the PC fan had stopped working and the computer would automatically shut down just after Windows loaded. I found a way to rewire the three (small)pin fan power plug to another output source on the mother board and I used an external fan-speed controller to reduce the full fan power setting (to reduce the excessive noise of the fan on full power).
Prior to this, I had had some kind of electrical problem - when I took out a USB/firewire plug from the back of the computer and it wouldn't boot up. As a result, I figured out that I had to flash the bios, and use the first part of the OEM disk which helped to automatically repair the book block to get the computer to recognize the hard disk and to boot up normally again.
Then, now, one year later, the same kind of problem had happened again: after taking out a USB plug from with back which seemed to cause some kind of electrical short -- the N-VIDIA 5200 graphics card wouldn't display and the main PC fan and Intel Chip fan weren't running. I sent the computer to the Shuttle representative company here in Japan, Mouse Computer, but they wanted to charge more than the cost of a new computer to repair it (more than 10 times the price of a new graphics board!) ???!!!
Anyway, I took back the computer without them 'touching it', and I figured out that I am able to see the video display by using the alternate video output plug which can be found on the other side at the back of the computer, but this is is only in the case of removing the AGP video card so that the slot is empty - the computer then utilizes the internal Sis graphics.
I found a program 'Intel Extreme Graphics 2" loaded into Windows, so the repairers might have installed it to make the screen quality a bit better. I used a big house fan to blow air into my computer which had the cover off to keep the computer cool and to be able to be operated on.
Being able to see the screen and operate Windows, I flashed the bios (fb61s30s.bin) with awardflash (awdflash) after booting an NTFS Dos CD I had the awardflash program files and the bios bin file copied onto another CD which I activated after loading the dos in memory with the previous CD.
The fans still don't work and I don't think buying a new video card will get the AGP video card working, so I think I'll persist with the current video source.
I now need to find a way to get the fans powered -
I am thinking of sourcing the power from the large 4-pin connectors ...
As Ben above said, and as I experienced, it seems that if you are unlucky, there may be a time when both 2 smart fan motherboard plugs will fail to work.
As Mark realized, and as I experienced, it seems that if you are unlucky, the motherboards might play up soon after the warranty expires.
And as Gerard22 pointed out, the representative company of Shuttle computers, don't care about helping customers. They are making enough from the sales and try to profit from the repairs as well - here in Japan, the Shuttle representatives, Mouse Computers, (
http://www.mouse-jp.co.jp/easycube/index.html) say they will return your computer with the hard disk wiped clean if you send it in to them for repairs (in order to be in the original state that you got it), and they will quote repairs that are factored to be several times more than the cost of new parts and justifying it as being the price of the items at the time that the computer was purchased! They have also reduced available optional warranty for the SB61 to one year instead of 3. I noticed that they used to have a greater range of Shuttle models, but now an improved SB61 seems to be the only Cube type they are sticking with.
Nevertheless, the computer that I am talking about that had major problems is my work computer, and I actually bought a similar one for my home about a year after, and it is working fine (though I have an unknown pink lines problem on my screen every now and then). Anyway, as a final note, you may need to put up with these kinds of problems, the poor service of Shuttle representative companies, and figure things out for yourself. I like Shuttle and hope that they get these issues ironed out in future models.