After close to 6 years for my last build, I'm currently looking to put together a new build based on a Core i7 8700 (not K, because I never overclock) on either a ITX or micro ATX MB, using 1 M2 + 1 2.5inch SSD drive, and carry the old GTX980 over for the rare gaming moments with the potential to upgrade to one of the new GPU later down the line (eyeing 1070 or better). I'm looking to drive an ultrawide screen monitor with 3440 x 1440 resolution. With minimal parts to play with I'd thought it might be worth looking at SFF cases again with small foot prints (eg Silverstone RVZ03, Phantek Evolv Shift or some other small cubes from Lian Li). Long story short - my last build was once housed in a Silverstone FT06 Mini which uses SFX PSU and the Silverstone PSU fan noise got so annoying because the it would constantly kick even when not gaming in so I ditched that case for something bigger so I can go back to a Seasonic ATX fanless PSU and a large Noctua tower cooler etc and got everything quiet again.

So my question is, how good (quiet) are the modern SFX PSUs when used in a small gaming build? Will the noise be audible in non-gaming usage? Or are they still not good enough that I should forget SFF cases and go with something that takes ATX PSUs? Or if I should go the opposite direction and give up on gaming on the PC altogether in which case the load would probably not get the SFX PSU fans to kick in?

They are probably much better than they were 5 years ago.

SFX PSU's still suffer from the limitation of 120mm fans needing to spin faster than 140mm fans to achieve the same airflow. Thankfully, in recent years, newer desktop PC components have been consuming less power so smaller power supplies do not need as much load.

My SilverStone SFX PSU works in fanless mode until the temperature has reached 55℃.
I doubt whether 55℃ is acceptable.

Corsair have recently released two hybrid modular Platinum SFX PSUs, the SF450 and the SF600. According to them the fan on the SF450 stays off below 90w system load, and below 120w for the SF600. As Platinum units they aren't exactly cheap, the 450 is £90 in the UK and the 600 £105, but they do seem a real improvement on what's been available so far. This suggests that either should be silent in a non-gaming scenario but for a gaming setup there could be some fan noise. Whether that would be a real issue is difficult to say. The fan profile of each unit is slightly different. But Corsair do seem to be attempting to keep fan speeds down to reduce noise, at least up to around 50% of nominal capacity. For full details see this PDF download from Corsair.

Another Platinum, SilverStone Nightjar NJ520, has no fan at all and is not cheap at all.

If you mean the ones below, they should be Gold rather than Platinum.
https://www.corsair.com/uk/en/Power/sf- ... 9020104-UK

What seems to be happening is that there are existing Gold versions with the same designations. But a Platinum version is on the way, the Platinum SF450 for example has a different part number, CP-9020181-UK to the Gold equivalent. Maybe Corsair should have adopted a slightly different model designation to make it clear there were going to be two versions of the SF450 and SF600.

The same Corsair UK web site does show the SF600 as Platinum as you can see here. Confirming there are two versions, from the text on that page "...The SF PLATINUM Series’ high-density design delivers high efficiency and low noise in a compact SFX form factor without compromising continuous power, reliability, or quality."

My local supplier is taking pre-orders for the Platinum models with mid-July availability expected. Incidentally, I note that "...SF PLATINUM Series power supplies include an SFX-to-ATX power supply adapter bracket..." which I think is the same as the Gold units. It does mean that when the SF450 is available it will be the cheapest ATX-compatible modular hybrid Platinum psu on the UK market.

Is it worthwhile to spend so much money to buy Platinum?
Can it really work for 100,000 hours (MTBF)?
On another forum, someone said a quality PSU could be used for 2~3 decades. I doubt that.

If you can afford the premium price, then yes Platinum psus are worth it. Bear in mind that there other things that push the price up, for example hybrid fan control and modular cables. There are also constructional differences over cheaper PSUs, principally the quality and temperature rating of the capacitors.

The cheapest SFX power supply from my normal supplier in the UK is the Seasonic SS-300SFD 300w at around £35. This is a White unit (i.e. one tier below Bronze) with no hybrid fan control, no modular cables and a warranty of 3 years. The SF450 Gold is £80 and the Platinum £90. So yes the Platinum unit is £55 more than the cheaper unit. The greater efficiency of the Platinum unit would give a degree of payback through less use of electricity and a lower cost of running it. The other thing in favour of the SF450 is the 7 year warranty, although the 100,000 hours MTBF would be more like 11 years.

PSUs are probably the most long term element of any PC build and it would not surprise me if 10 year old and over units were still in operation. This would particularly be the case for PSUs which have no current replacement available such as the Antec CP-850.

The hybrid fan control is pretty nifty. My five year old Seasonic is placed in the bottom of an Antec P180 along with some SSD's that does not require extra cooling, and the only time when the Seasonic PSU starts the fan is during stress test or occasional gaming. If not for the hybrid fan control I would have to install a fan for cooling, just in case.

So, a 660W PSU is overkill when out-of-wall draw is at most 250W, but at the time "lesser" PSU was fanless and for me a worse choice.

So far, my SilverStone SFX PSU has never started the fan.
So, is Platinum more durable than White? What would you say about this opinion: http://computer.discuss.com.hk/viewthre ... d482323353?

Platinum is significantly more efficient that White. So for any given power draw it will pull less electricity from the mains supply. It will also dissipate less heat in the process. Achieving this improved efficiency needs better quality components particularly capacitors. This does affect durability. One measure of durability is the length of the warranty period, typically 3 years for a White unit versus 7 years for a Platinum unit.

viewtopic.php?f=6&t=70092

As lodestar posted in the above link a fanless SFX PSU

https://www.silverstonetek.com/product. ... 42&area=en
A Gold SFX PSU with a silent fan (18dBA minimum).

On another forum, someone thinks that Platinum = high efficiency = complicated design = prone to problems = instability. What do you think?

Having used both Gold and Platinum power supplies I would say there was no difference between them in terms of reliability and instability. On the complicated design point it seems to me that a more PSU complex design may well be more reliable if it has better quality components; less good quality components may only work if used in a simpler design. So I don't think the complicated design=instability idea really applies to power supplies, the already mentioned length of the warranty periods are a perhaps the best indicator of that.

It might be, and it might not, really will depend more on the design and the components themselves, you cant generalized as a hole imo. Now if we go by that premise, Titanium would be even more complicated and prone to more issues, and i own 3 titanium PSU for a year now, no issues at all, i also own 3 platinum for 3 years and also no issues at all.

Now on the worth pov, i think Gold is a pretty solid standard, coming from Bronze (i never saw silver take over), the difference is big in my experience, most PSU are more quiet, and now its as cheap as it was bronze in back in the day, the upgrade toward platinum is a small one, but also the pricing is very tight now a days (on ATX, sadly not that many options on SFX PSUs), now one thing to keep in mind is that usually SFX PSUs have smaller fans, 80 to 92 mm are more common, some PSU cooling design are based on load others on temperature and some with both, now a platinum PSU should be slightly more efficient thus losing less energy in form of heat, in theory should be a little quieter (something that might be so small that might not be worth it, again depends on each design).

I have preordered the Corsair SF600 Platinum for mini itx build, but its been a month and hasn't shipped from amazon, not sure whats the deal, corsair said august will hit retail, now we are on September and no stock, gives some second thoughts, but its more likely they are trying to lower their stock on the gold versions, but personally i can see them both co exist with a slight price bump. I'll share my thoughts once i get it.