Thanks for the insight. So the Corsair HX850i itself will physically overlap the bottom fan, or are you "just" saying that its cables will hinder the airflow?
Cables will hinder it no matter the length of the PSU, but i dont think its that bad though, its just like the last end of cables while they turn to the grumeted hole. But what i was saying is that the ideal length is 160mm, you can see my build on my signtature where i use R4 + SS860XP2, you can check the NF-A14 PWM on the bottom, you can judge if you think a 180mm PSU like the HX850i will fit, my guess is no, you wont be able to use the bottom fan, specially into how the HX850i has all rows of modular cable connectors used. One of the reason i didn't went with the LEADEX 1000W platinum was its length, to date i think its the best PSU in the market, just hell of expensive and probably not worth its premium price with so many in the range of $150-200. Either way decide first if you want to use or not the bottom fan slot, second decide if you want a 120 or 140, then decide on the length of the PSU.
Thats very good point. I must admit i figure it would be quiet "enough", but with a GPU that can go completely silent when idle, and possibly the same for the PSU (depending on choice), it might be a good idea to pay more attention here.
The most important thing for you to decide on the CPU cooler is the width of it, in Z97 motherboards you will pass the 1st PCie slot with the NH-D15 for sure, im not totally sure if the LGA2011-3 socket is placed further up in the motherboard to allow to use a cooler like NH-D15 and still use the first PCIe, this is heck of important for someone planning a sli. Personally i think thermalright is ideal for this for its asymmetrical design that grown more toward the top of the motherboard than it goes into the gpus, but each of us have their own preference in brands and coolers, but be very careful to avoid needing to return and get another cooler.
The recommended SLI configuration for an 28 lanes CPU is the 1st and 3rd slot (running at x16/x8).
Thats sad, really dont get it, in terms of having the 2nd 16X electrically wired on the 3rd slot. Now i would try to find a motherboard that give you a little more room, this is more common the Z97 with dual slots between 16X (even though its 8x 8x once you ocupy both). GPUs will probably be the most noisy component, but thinking the STRIX will be passive most of the time, the better you get airflow between the cards the more it will remian totally passive and when it does spin more airflow will also allow better cooling again needing less rpms to keep the gpus under control. From what i remember 80C is where Nvidia is throttoling the cards or the turbo boost, so try to have good airflow between the cards so you dont reach this.
Actually hadnt realized that the 850Pro was available in 1tb. However its also crazy expensive in comparison (330€ vs 520€). But perhaps i could make do with a smaller size (say 512GB). I should probably check out the benchmarks in more detail...
In benchmarks the 850pro is the king of all ssds, but for the real end user the difference are not felt, SSDs biggest strength is their 0 latency, which all ssds will give you that feeling, after that is mili seconds that for the average user it will not be perceived. Now 850pro does come with best warranty on the market, 10 years, so samsung is betting on it very hard, i would assume they know what they are doing if they are backing it up, it can stand a lot more writing and punishing than the usual ssds, still is not enterprise level, but its above average. Now weather you need it or it justifies its price is something that only you and your wallet can answer, personally i recommend crucial MX100 512gb superb ssd for what it costs, not the fastest, but performs very well, and for the average user they will never feel the difference over a 850pro, and the money saved could be easily used toward a new GPU =).
Is the seasonic's prone to coil whine compared to other brands? Any particular alternatives i should be looking at?
I own 4 seasonics atm, one X400, X660 and 2x SS860XP2, and to me none have coil whine, well the x400 has a small electrical buzz if you stick your hear next to the grill of the PSU, but its unperciebable at 30cm away, and i sit well further than that, so its not an issue, on the other 3 i own, i dont hear anything at all ever, so for me seasonic is still the best in my book (well 2nd to leadex). That said, the biggest complains you find on user reviews on seasonic platinum are coil whine, something that any electronic is prone to, specially caps, that said, is not something that happens to all, and personally i believe is a combination of hardware that might trigger this, i can tell you honestly that i don't have any issues, but i do like to warn people before committing to seasonic.
About other brands, in platinum, i like Superflower LEADEX but its heck of expensive. Corsair HXi series are getting great reviews, but its drawback is the length on the R4 if the bottom fan is planned, else is fine, Corsair AXi sereies is also their top of the line, so it should be a good option, from what i recall the none i were seasonics and AXi were Flextronics and CWT, but they are still among the best psu in the market. Some people like a lot BeQuiet DARK POWER PRO 10 series, so it could be a good option as well, specially since its more available in Europe than its on the US. Delta Antec PSU still great, but i don't think they are very quiet under load, Enermax is another brand that imo was one of the best in its time, i have avoided them more out of having mulitple 12V rails, even though i dont think its a big deal, i don't like having to think my lines to balance each rail.
If you drop into gold certified that shoudlnt be that much different, there are options like Quest recommendation that i tested and i can say its a great PSU, the EVGA SuperNova 750 G2, for what it cost in the US, i dont think you can get a better PSU, its based on the Superflower Leadex design, and gotten really good reviews from high end psu sites, the problem is also a big psu in length, so you will have same issue as the HX850i on the R4 using the bottom fan.
I hadn´t been planning for any extra/replaced fans initially, i wanted to see how things worked out with the out-of-the-box fans for the various components.
] The R4 comes with only 2 fans from factory, both 140mm Fractal R2, that are decent but not great, either way i would recommend a little more airflow for a SLI setup, personally im running 3 intake and 1 outtake, i like a lot more to have positive pressure than negative to avoid excessive dust buildup, and since the frontal fans are restricted and behind filters i went with 3 to ensure i ended up with positive pressure.
As final recommendation, i think you liked the HX850i, seems like a great PSU, and they have gotten really good reviews from high end PSU sites, so its a very nice alternative, but for the kind of hardware you are planning, i would consider something like FT05 and since you are going with Asus have FanXpert2 tame down the 180mm fans, since you are not going with mechanical hdds, you can remove the hdd cage and still be fine with a long 180mm psu, the only thing that i dont like on the FT05, is the cablemanagement where you will need to be a little creative. Im probably will be moving toward one in the next month or two, and if you haven't bought by then i could give you some feedback about it, but im still not moving toward SLI, dont think 2 cards will be able to move a 4k res yet, so ill move next gen.
Now if your mind is set on Fractal, for whatever reason, and you like the HX850i, then consider changing the R4 for XL2, from what i have read, the bottom of the fan placement is different and allows biggers PSU with the bottom fan slot used, i think you might be able to use an 180mm PSU with 140mm fan on the bottom, but its up to you to crosscheck this, as i dont own one to tell you for sure.