System crash when Cycles render - Workaround is inefficient

My work system specs are as follows:
Windows 7 64bit, Blender v2.71 64bit
Intel Core i7-4770K @ 3.50GHz
Nvidia GeForce GTX 770
16GB Ram

I have been using blender for some time, but always encounter a problem on this machine with rendering in cycles. The system is prone to crashing on cycles renders after the first few tiles have rendered. I am using GPU CUDA rendering to make the most of the hardware available, but the crashes happen unless I set the tile-size to 32 x 32 or smaller. At 64 x 64 it will crash within minutes, and at 128 + it’s almost immediate, like after the first 3 or 4 tiles.
Setting tile size to 32 x 32 allows me to render, but I know this is not an efficient method. I have done tests and when lucky, a 128 x 128 tile render will complete and be MUCH quicker than 32 x 32.
I can’t find anything in windows event viewer regarding the crash, but the whole system stops, I get a gray screen and it does not recover. I have to manually reboot.

Things I’ve tried include:
Rollback/change drivers for the graphics card.
Update BIOS
Update Chipset drivers
Update Blender (this has been an issue for the past few versions for me)
Underclocking GPU (I can’t be certain this seems to add stability, but ultimately the same issue occurs eventually)

Other things to note:
CPU rendering works fine.
This is not a gaming machine - I’m not usually stressing the GPU unless I’m doing these renders so a fault with the GPU is possible, I’m going to work on testing this theory with other stress tests.
I have thought about it being a power issue - related to the PSU, but the system is otherwise stable, and the PSU is plenty big enough to cope.

Any suggestions for a solution or methods for diagnosing the cause of these crashes are welcome.
Thanks for checking out my issue.

Try a more recent build of Blender to check if there might have been a bug in the official 2.71 release that has now been ironed out (you can just unzip that to where you want and start Blender from there).

Other than that:
Complete system crashes when GPU rendering are not that often to be found around here - if at all. This rather seems hardware related. What do the GPU temps say during rendering? And is that a 2GB or a 4GB GTX 770?

Thanks for the reply.
I’ve just updated to the latest build as you linked. I ran a new render at 128 x 128 tiles and the GPU temp hovered around 58°, usage was 98-100%. The system crashed to gray screen after about 12 tiles.
The card is 2GB.

Well, at least we can rule out a thermal problem now.
But still, a grey screen crash is imho a strong indication for a graphics card problem. Since you reinstalled your graphics drivers already, the problem indeed seems to narrow down on a possibly defective graphics card. Do you have another PC at hand to test that card in? Or the other way around: Another card that you can test Blender on in your current machine?

It’s looking more that way - I can take the card to try and replicate the crash on my home system, this at least would rule out a few more possibilities.
I just ran Furmark stress test and it crashed after several minutes, so this issue is no longer relevant to Blender, but if anyone else encounters the issue they can at least see what it could be related to.
I’m going to swipe the GTX 770 out and stress test it on another system.
Thanks again for your help - I’ll reply with what I find out in a day or two.