Aside from the blower fan on the graphics card (which appears to be a modified Corsair Hydro GFX, also known as an MSI Sea Hawk), the only fan in the system is the one in the top. When I first saw this I became really concerned about the thermal performance of the One. So, how is it?
In a word: excellent. Actually, I'm a little bit stupefied at how well the cooling in the One works. Whether playing GTA V at 4K with the settings slammed to the ceiling, or gliding through the gorgeous Unigine Superposition demo, the One stays pretty cool.
I did manage to heat the machine's Core i7-7700K CPU to 85° C briefly, before the fan kicked up a little and things cooled down. That was with a home-brewed torture test that consisted of running Unigine's Superposition benchmark while transcoding a 4K video using x264. During normal testing, the CPU never topped 72° C, and the GPU itself never broke 60° C.
Those thermal ceilings were good for a 4.5 GHz all-core CPU Turbo speed out of the box (thanks, MSI multi-core enhancement!) and an 1847 MHz GPU core clock. Those figures are at least as good as what one might expect from a full-size desktop PC with similar specs, which is quite impressive given the One's small footprint.
With that thermal headroom in mind, I cranked the GPU's power limit up to 120% and it heated its way up to a scorching 61° C. (For those who aren't aware, Nvidia specs the GTX 1080 for a maximum temperature of 94° C.) Unfortunately the MSI-built GeForce doesn't allow me to raise the voltage any further, so I ended up voltage-limited at 1898 MHz. If you want to overclock this GTX 1080 further with Afterburner, at least it shouldn't be thermally limited.
I didn't try overclocking the CPU, but the firmware in the One's MSI motherboard doesn't have any locks on its multiplier or voltage settings, so you could conceivably take the Core i7-7700K to the thermal and noise limits of the One chassis if you wanted.
Those results aren't bad in any case, but they're even more fantastic given that the One almost does not make audible noise. I am not exaggerating when I say this. I went to considerable lengths silencing my normally-quite-noisy home and I can't hear this thing unless I run a benchmark and then place my ear directly next to the exhaust fan. Corsair says the One was designed for silence and tested in an anechoic chamber, and I believe it. The other mini-PCs I've tested have been impressively quiet, but this machine is on a whole other level of silence.
We didn't spend a lot of time on detailed performance testing with the One, because the Core i7-7700K-and-GTX-1080 combo is such a well-quantified platform by this point. Suffice it to say that without many (if any) thermal or power limitations, the One will perform as well as a similar full-size desktop. That's really quite mindblowing given how much larger the average ATX case is compared to this little tower of power.
Get with the programs
As a prebuilt system, the One comes with a copy of Windows pre-installed. I didn't test it exhaustively because we do our testing on a clean copy of Windows, but there wasn't a whole lot to test anyway. Corsair keeps the bloat that tempts many other manufacturers at bay.
Corsair boasts that it ships the One with a pretty fresh Windows install. Indeed, when I hooked up the machine it booted directly to the Windows 10 desktop with little else loaded. A small icon near the notification area allowed me to launch the Corsair One Diagnostics app. This is basically a re-skinned version of PC-Doctor. If you aren't familiar, PC-Doctor is a decent little app to help folks who aren't as computer-savvy as the rest of us make sure everything is running smoothly. It can also be a useful first-step diagnostic tool when working on a friend or family member's PC.
Corsair also shipped the One with its Corsair Link software installed. This is the app that you would normally use to monitor and control the performance of Corsair's stand-alone liquid-cooling hardware and Corsair Link-enabled power supplies. The options available on the Corsair One, at least with the pre-installed version of Link, are pretty limited. In fact, just about the only use for Link on the One is to toggle the cyan lights on the front between off, breathing, or fully-on modes. You can use it to monitor temperatures and fan speeds, but it's a bit cumbersome to use for that purpose alone.
Besides those two apps, Corsair included its SSD Toolbox app for the Force LE SSD, Nvidia's GeForce Experience, and... that's it. I considered testing with the included OS to save myself the time of freshly installing Windows, but with a machine this fast it wasn't even half an hour before I was installing games and running benchmarks. Out of the box, however, I have no complaints with Corsair's largely bloat-free setup.