How long will my pc last

Any  opinions or suggestions on improvements or changes? 

Without knowing what you  plan on doing with the machine, it impossible to speculate how long it will viable for what you plan on doing with it.

And without a budget, we can't recommend changes.  

I would get lower profile memory, such as 1866mHz CL9 1.5V (not the 1.35V stuff) G.SKILL Sniper series or Ripjaws X, to go with an air cooler, like a Phanteks PH-TC14PE, Noctua NH-D14, or bequiet! Dark Rock Pro 2, which will perform as good as, or, most likely, better than the H100i, while being cheaper.

Get a smaller PSU, such as a Seasonic G 450, Rosewill Capstone 450M, or on the larger-end of the wattages, for dual 780s in the future, a Lepa G650, Seasonic X650, or, again, the Rosewill Capstone 650M. You don't need anywhere near 850W for a single GPU, that's enough for at least two heavily OCed 780s and a power hungry CPU, and even up to 3 GPUs, even the venerable 780.

Lastly, I would get a 4770k and Gigabyte UP4 Z87 with the money that you saved from the previous changes. Much better per-core, better performance at lower clocks and per-clock, and native PCIe 3.0 (or 3.1? Faster than the native 2.0 of the 8350), and USB 3.0, among other things. If you want to keep with the 8350, drop the Sabertooth and go with a Gigabyte UD5 990FX; it doesn't have the gimmicky PCIe 3.0, which the 8350 doesn't support, but it does have a stronger VRM for OCing, a better color scheme (personal preference), and a solid overall feature set, at a lower price.

I'd say, objectively, though, that an 8350, 780, and 16GB of memory would last, oh, about 3 years with modern games, and the 4770k system roughly the same, but possibly a bit longer. At least 3 years for either. I only assume you are gaming, so if you aren't, please, specify :) 

Looks good if you want to spend that much, i guess the 850w psu is for crossfire/sli.

The 290x is probably better than a 780, considering mantle and the consoles being amd there are even more plus points. That build is way stronger than the consoles and wont have a big optimisation disadvantage, youll probably be able to play any game for the whole cycle in 1080p with adjusted settings. However, the consoles will render most games in sub 1080p, much like the current gen, while pc gaming is going towards 4k, that will need some serious GPU power.

sorry for not specifying i forgot ;) but i will be gaming at 1440p using CAD, Photoshop and other Adobe programs, video editing and rendering running a couple of monitors and some intense productivity, and what is the major difference between the 4770k and fx-8350 

Biggest difference between the 4770k and the 8350 is per-core performance, per-clock performance, and power consumption. The 8350 has 8 physical cores (4 modules, 8 cores), compared to the 4770k's 4 cores and 8 threads (HT), but the 8350 has much, much worse per-core performance; in my vastly unscientific testing, SuperPi 32M, which is single-threaded, was running on my 3770k in under 7 minutes and 30 seconds, while the 8350 of other users, at the same clock (4.6gHz), was running around 21 minutes.

Haswell runs very well at lower clocks, compared to Ivy, Sandy, and Vishera. I don't have hard numbers, but a slight OC on a 4770k, around 4.2gHz, is going to perform the same as a 4.3gHz Ivy, roughly a 4.4gHz Sandy, and around a 4.4gHz Vishera in multi threaded applications.

Lastly, Haswell is a much lower-wattage chip compared to Vishera; roughly 30W lower, iirc. Just a benefit of being a more modern architecture with a bit tighter power usage. The difference in the end, i.e. the power bill, isn't really noticeable, though, but it is something that bothers me.

But, power = heat...

thanks brennanriddell, but a fx 8350 is still about £100 cheaper so how does it compare then?, also what do you mean exactly about lower profile memory and how will it be a improvement, also is'nt 650 watt psu a little small as i will over clock the CPU GPU and RAM and will add another GPU into the mix later on.

Thanks again ;)

No, not necessarily. Wattage, i.e. power, is just potential * current, so you could have the same wattage at an infinite different amounts of potential, which is what really generates the higher heat in CPUs nowadays.

Lower profile memory as in physically smaller modules height-wise, so that they fit under the large CPU heatsink, and aren't some huge, gaudy sink (again, objective opinion).

650W is enough for an OCed CPU and GPU, even two GPUs, but you may want a 750W for better efficiency/load/lifespan ratio.