manofchalk :
The relationship between the 770 and 780 is nothing like it was between the 670 and 680, you wont get a 770 to overclock even close to a 780's performance.
You could do that with the 670-680 because they were the same card except some CUDA cores and a clock speed bump, the 770 is essentially an overclocked 680, while the 780 is a Titan with half the VRAM. An entirely different GPU (GK110 vs GK104), wider memory bus and an extra GB of VRAM cant be made up with overclocking.
My opinion, don't bother with the 770 if you already own a 670/680, your basically buying the same card. Save up until you can get a 780 or two, that will give you a real performance boost.
Thanks for your reply manofchalk, most appreciated!
I see, I have to be honest I hadn't really thought of the fact that the 770 and the 780 were using different GPU's. That is some valuable information.
My main point of reference for any hardware, mainly CPU, GPU and Hard drive, is cpu benchamrk, which I assum most of you are familiar with? If not here is a link to thier GPU list:
http://www.videocardbenchmark.net/high_end_gpus.html
(Please note that all GPU scores are for SINGLE GPU's only, the software doesnt currently support SLI, unless it is built in such as the 690...)
As you can see from the table, the difference between the 670 and the 770 is quite substantial, around 1,300 points. whereas the difference between the 770 and the 780 is few and far, around 400 points. This is why I believe an upgrade to 2 770's would be worth it. I know, I know, these sort of benchmarks arent a true statement of how the card performs, but its a ball park right? As far as overclocking the 770 goes, I hear that you can overclock it quite well, which leads me to believe that it is possible to get 780 scores from a 770, And at £200 less who can argue with that?
As far as real world gaming is concerned, the 770 seems to make quite a remarkable improvement on the 670 there also, adding nearly 10FPS to every game on test. There are several websites that support this, just google it! =)
I am still undecided as to whether I can be bothered to be honest. In order for me to make the upgrade, I will have to first sell my current cards, and then purchase the new ones. I dont know if I can live without my PC for more than a few days, let alone a few weeks! Maybe I'll wait for the Xbox One to come out on sale, so I have something else to do while my PC is out of action. (Yes it will be completely out of action as my motherboard has no HDMI, VGA or otherwise connectors. Unless you can get a usb to HDMI adaptor that is!)