Gleich bei zwei Hardware Tester ist es zu Rauchentwicklungen gekommen, wobei in beiden Fällen unterschiedliche Motherboards verwendet wurden Bei Legit Reviews war es ein ASUS X99 Deluxe Motherboard:
Intel X99 Motherboard Goes Up in Smoke For Reasons Unknown

On Friday I spent the day wrapping up the benchmarks on the Kingston HyperX Predator DDR4 16GB (4x4GB) 3000MHz quad-channel memory kit (part number HX430C15PBK4/16) that runs at 1.5V. This morning I wanted to get another kit of DDR4 memory tested, so the system was powered down, the CMOS was reset and a G.Skill 16GB (4x4GB) 3000MHz memory kit (F4-3000C15Q-16GRR) and powered up the system. It posted fine, so I went into the UEFI and set it to run at the only XMP profile on the kit. The UEFI changes were Saved and the system restarted. It was during the next seconds that both the board and the processor would be killed off in a rather unspectacular death. The system came up, hung for a very short time and then powered off with a audible click of the Corsair AX860i power supply. If you’ve ever heard the loud click of the Over Current Protection (OCP) shutting down the PSU you know exactly what click I heard. Now when I press power button on the motherboard the system clicks after being on for a split second. I unplugged all the cables on the power supply and did the built-in self-check and it passed with flying colors. I still swapped out the PSU with a backup Corsair AX860i and the same click was to be heard. and it’s doing the same thing (Corsair AX860i). After clearing the CMOS, removing the memory, SSD and video card the system still wouldn’t post. At that point in time I switched to a non-digital power supply (Corsair AX1200) and it did the same thing although this time the OCP took a little longer to kick in. There was some audible crackling noises, followed by some smoke near the CPU VRM heatsink. So, the heart shattering smell of burnt electronics filled the room and I knew my day wasn’t going to be a good one.

... und bei Phoronix ein MSI X99 S SLI Plus:
My Core i7 5960X + MSI X99 Experience So Far: It's Smoking, Really

This weekend I was planning to publish the first Linux benchmarks for Intel's incredibly powerful Core i7 5960X Haswell-E processor with X99 motherboard and DDR4 system memory. Unfortunately, all I can tell you now is that it's smoking, quite literally!

The testing has unfortunately been delayed again since when powering up the X99 motherboard for the first time, it had a quick flame and then smoke from two locations. The motherboard in question was the MSI X99S SLI Plus.