Changing the PSU and CPU cooling

Either Newegg or Amazon are fine. I use Newegg more since they have a distribution center where I live in southern California, but I go to Amazon on occasion also. I've never had a problem with either one, although not everyone can say that.

I've dealt with both Newegg and Amazon frequently and have never had any issue with either. MicroCenter is also a wonderful place if you're lucky to live near one. You can shop online, but most of their specials are in store only.

Amazon has the AX860 for less than the 760 runs in most places including themselves.
http://www.amazon.com/Corsair-Modular-Supply-Platinum-Certified/dp/B00A0HZMKG/ref=sr_1_1?s=pc&ie=UTF8&qid=1460383437&sr=1-1&keywords=ax860

The 4790K is one of, if not the best, CPU Intel ever made. I don't see it bottlenecking anything in the forseeable future.

So long as your psu is doing the job, keep using it.
I do not know of the quality though.
One of the plusses for pascal is reduced power demand.
I think it likely that a strong card will not use any more power than your current GTX970 card.
I would wait on the psu upgrade.
Do look for reviews on the psu, and if it does seem to be a cheap unit, then, perhaps plan on changing it out.
Here is one list of psu quality:
https://community.newegg.com/eggxpert/computer_hardware/f/135081/t/45344.aspx?Redirected=true

I find liquid cooling unnecessary for current gen intel processors.
But, since it seems to be doing the job, I see no need to change it out.

For fast action gaming, the 4790K will be as good as it gets with even the strongest of graphics cards.

I do not recommend sli unless a single strong card will not do the job.
Regardless, you will want to see exactly how much power you might need.

I have no problem overprovisioning a PSU a bit. Say 20%.
It will run cooler, quieter, and more efficiently in the middle third of it's range.
A PSU will only use the wattage demanded of it, regardless of it's max capability.

Here is my canned rant on planning for dual cards:
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Dual graphics cards vs. a good single card.

a) How good do you really need to be?
A single GTX750t1 or R7-265 can give you decent performance at 1920 x 1200 in many games.
Yes, you may need to be satisfied with less than high settings.

A single GTX970 or R9-390X will give you excellent performance at 1920 x 1200 in most games.
Even 2560 x 1600 will be OK with lowered detail.
A single GTX980ti is about as good as it gets for a single card.

If you are looking at triple monitor gaming, or a 4k monitor, sli/cf will be needed for excellent frame rates in fast action games.
Not so much in mmo, strategy and sims.
A single GTX980ti or Furyx will give good frame rates in many games.
Next year, it looks like single card performance will go up by 50%

b) The support costs for a single card are lower.
You require a less expensive motherboard; no need for sli/cf or multiple pci-e slots.
Even a ITX motherboard will do.

Your psu costs are less.
A card as good as a R9-FURY or a GTX980ti will need only a 620w psu.
When you add another card to the mix, plan on adding 200w to your psu requirements.
75w for the slot, 75w for an extra 6 pin connector or possibly more.
Here is a chart:
http://www.realhardtechx.com/index_archivos/Page362.htm

Case cooling becomes more of an issue with dual cards.
That means a larger and possibly expensive case with more and stronger fans.
You will also look at more noise.

c) Dual gpu's do not always render their half of the display in sync, causing microstuttering or screen tearing. It is an annoying effect.
The benefit of higher benchmark fps can be offset, particularly with lower tier cards.
Read this: http://www.tomshardware.com/reviews/radeon-geforce-stutter-crossfire,2995.html

d) dual gpu support is dependent on the driver. Not all games can benefit from dual cards.

e) dual cards up front reduces your option to get another card for an upgrade. Not that I suggest you plan for that.
It will often be the case that replacing your current card with a newer gen card will offer a better upgrade path.
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