This was the culmination of a 2 month experiment into building a totally silent Workstation to handle all of my daily Computing needs from simple web browsing to Video encoding and 24x7 computational demands. It was designed to replace quietish but 4 year old and getting noisier i7-2600K build.
Initially I started out with a Thermaltake Core V1 case, a Silverstone SFX 300 W Semi Passive PSU and a Intel i7-5775C CPU. I opted for this CPU rather than the Skylake CPU's as when the Skylakes were announced the 91W TDP of the 6700K was simply too high for any totally silent CPU cooler.
Testing with a cheap Pentium G3258 CPU went well but when using the i7-5775C though the temperatures were OK there was a whining noise generated when the CPU was under full load and if you added stress to the onboard GPU at the same time the whining got much worse.
The whining had to go and I decided I also still needed a DVD drive so I went looking for the NoFan CS-70 case. A stripped down and more heavily ventilated version of the Silverstone Fortress FT03. But it seemed that my timing was terrible as none of the people that previously sold it seemed to be able to get hold of it. So I plumped for the actual Silverstone standard version instead and stripped out all the fans. Though it does not have as much side venting as the NoFan version the bottom is almost completely ventilated. I also purchased an XFX STX 460W passive PSU (the Parts list shows a Seasonic one but as far as I am aware it's basically the same thing). I also installed this upside down. I know the manufacturer was very explicit about the vented side being at the top - which makes total sense - but as this case vents in from the bottom and directly above the PSU is the DVD drive there would have been no airflow. So I went for the upside down option. With the total power it was going to pull being less than 100W I am hoping this won't cause any issues long term. Certainly nothing noticeable so far.
This built up into a nice fast system. PassMark scores of close to 11,000. Idle Temps of around 33C and though it ran at around 90C under full stress in closed system it never complained or fell over due to heat. It did however start to show issues as I was starting to use in daily use. This ultimately was discovered to be due to a Microcode issue in the Broadwell Chips that produced MACHINE_CHECK_EXCEPTION errors under usage in certain software. Outlook 2016 caused failure everytime you launched it. Other Office 2016 apps at random points. This is a known issue and with no BIOS updates from ASUS there was no choice but to change the CPU.
I ummed and ahhed about swapping the Motherboard and Memory at the same time to go for a Skylake i7-6700T as these were available by this point but decided to go for the cheaper option of going for an i7-4790T in the end. This I believe was a wise decision as I have subsequently heard that the i7-6700T though rated at 35W still draws more power than the 45W rated i7-4790T. And they both have very similar PassMark scores of just over 9000. Have to say the Skylake processors don't seem to be bringing much new to the party in comparison top the 4th Gen chips.
The NoFan Cooler is a very tight fit for the case with this motherboard and needs more than a little persuasion to fit. Going for a MicroATX motherboard with the CPU socket slightly further towards the PCI Express sockets (even just a couple of millimetres) would be a much easier fit. I did try the smaller NoFan CR-80EH as this is rated to 80W but it seemed to really struggle with cooling even this 45W CPU. Even at Idle the temperatures were hitting the high 40s. Perhaps something I did wrong. In the end I went back to the larger CR-95C.
With the i7-4790T installed the full testing started. Office 2016 ran perfectly. Idle temperatures of around 30C and Full Load temperatures of 73C even after 12 hours of Prime95 stress testing. This was with a undervolt of 0.050V. Trying 0.100V undervolt resulted in crashes fairly quickly in Prime95. Have not yet tested any variations inbetween. According to CPUID HW Monitor the CPU pulls a 45W during Handbrake Video encoding and the max power seen so far under full stress testing is around 53W. As a comparison the i7-5775C with a similar undervolt was running at 65W for Handbrake and 80W when doing full CPU and GPU stress testing.
Though it's been a long journey I now have a totally Silent PC - indeed the loudest part of the system now is my the very gentle hum from my monitor which I can only hear when the rest of the house is quiet. The case, though bigger than my original plan, is good as it looks stylish and it includes a DVD drive and also a hotswap Hard Drive.