This is my second Corsair One, replacing an i160 that served me flawlessly for three years. That machine is still going strong- my daughter now has it - but I decided to upgrade to the newer model. The new i300 is much faster and slightly (and surprisingly) quieter - and all in the same small footprint case.The build quality is excellent. What may not be readily apparent from the ad photos is that the case is made entirely from aluminum - from the base, to the front and side panels, to the fan grill on top. The only things plastic are the start button on the front and the IO shield on the back. The case is basically one giant heat sink.The components do get hot - the i9-12900k CPU, in particular, which runs notoriously hot in any PC. But the liquid cooling system in this machine works very well, especially for such a small form factor PC. If you plan to run applications that constantly stress the CPU at full load, I suspect there will be some thermal throttling. But for my uses - office apps, photo editing, and games - I've had no issues at all. Neither the CPU nor the GPU comes close to their maximum temperature limits, even in graphics intensive games like Cyberpunk. Heat has been a non-issue for me, even with these challenging components.The PC is also quiet - surprisingly so even compared to my older model. The main exhaust fan at the top is controlled by Corsair's iCue software, which allows Default, Custom and Extreme settings. Default is a quiet mode, where the fan starts at 0 rpm and ramps up, as needed, as coolant temperatures increase. Extreme is the opposite - the fan runs full blast (2000 rpm) all the time. Custom allows a fixed percentage anywhere in between - it's not a curve per se; instead, you can set a fixed percentage anywhere between 0 and 100 percent rpm. The fan then runs at that fixed percentage, but like thein Default mode, the fan will ramp higher as needed. I use either Default or Custom (@40%) and all is good. What has surprised me is that, while the fan has a maximum rpm of 2000, it rarely runs above 1500 even in the most demanding games. And the fan Corsair uses in this model has a very low hum, rather than a high-pitched whine, so the fan at 1500 rpm is hardly more noticeable (to me anyway) than the background noise in my office. It's actually a bit quieter even than my older i160 because the fan pitch is lower.Finally, while the thermal and acoustic performance is impressive, the small case remains the chief attraction of this PC. And the main motivator for me. There are many other PCs with equally fast components. And in a bigger case, with more fans, I'm sure the temperatures would be lower. But I've seen nothing with this performance in a case so small and quiet. And because the case is taller than wide - which actually is part of the convection cooling design - it takes up very little desk space. Not much more than my desk lamp. In that respect, it's the only PC I've ever owned that my wife doesn't complain about.I'm very pleased with the upgrade overall. My i160 was, by far, the best PC (prebuilt or DIY) I've ever owned. The i300 is a worthy successor.