So Long, Sandy Bridge

Way back in 2011, I built a nearly-silent gaming PC in a hulking full tower case that took up about half of the space under my desk. It was built around the Intel i5-2500K, a Sandy Bridge chip that could just as easily have been named The Little Processor That Could. That thing was crazy overclockable and, amazingly, it powered my primary PC until this month, when the motherboard started failing. I guess Moore’s Law really is dead.

I was an AMD fangirl when Bulldozer was released and, having been scarred for life by the experience, was too skeptical of Ryzen to want to become an early adopter. It’s a shame, because Ryzen seems to be reviewing very well. I stuck with Intel and went for a Kaby Lake i7-7700K on the theory that it would be a more stable platform. The reality is that I encountered some truly bizarre problems with this chip that I want to share in this post.

The Build

When it came to part selection, I made pretty standard choices for a gaming-oriented build, though the storage choices look a little strange because I kept my old SSD to use as a Steam drive. Here’s a quick list of the parts I used:

Component Selection
CPU Intel Core i7-7700K
CPU Cooler Corsair H100i v2
Motherboard Asus STRIX Z270G
Memory Corsair Vengeance LPX 32GB (2x16GB) DDR4-3000
Storage Samsung 850 Pro 2.5" SATA III 512GB
Samsung 850 EVO 2.5" SATA III 500GB
Seagate BarraCuda 3.5" 7200 RPM 2TB (ST2000DM006)
Video Card Asus GeForce GTX 1080 8GB ROG STRIX
Case Fractal Design Define Mini C - Window
Power Supply Corsair RM650x
Operating System Windows 10 Pro OEM
Sound Card Asus Xonar DGX 24-bit 96 KHz
Case Fans CRYORIG QF120 Silent (x3)

Everything worked pretty much as advertised, though the first video card I received was DOA: it produced all kinds of sinister graphical artifacts like blinking squares, streaks of white light, and missing textures, making my attempt to play The Witcher 3 the stuff of nightmares. I’m sure that if I had to go through an RMA with the third-party Asus farms them out to, we’d have an entire rant section of this blog post dedicated to it. Luckily I bought everything from Amazon, so I was able to just return the card and get a new one with overnight shipping. Bless you, Jeff Bezos.

I had done a fair bit of research before buying anything, so the performance I got was exactly in line with my expectations. All in all, I was neither over- nor underwhelmed. I was perfectly whelmed… until I started looking at my CPU temperatures and noticed how often the fans were ramping up.

You see, originally, I was using a budget air cooler – the Cryorig H7. The H7 a pretty decent little tower cooler and should’ve been more than adequate for an i7 at stock speeds. Its poor little fan was going insane. Most of the time it was nearly silent, as its fan was able to run at very low speeds. But seemingly randomly, the fan speed would spike so badly that it sounded like an airplane was taking off. Figuring out what was going on led me to discover – and eventually solve – two separate thermal problems with the i7-7700K.

Thermal Problems With the i7-7700K

I say two separate problems because while they both involve the chip getting too hot, they have very different causes and solutions.

The first problem was that the chip was running unreasonably hot period – we’re talking 40-50 degrees at idle – using my motherboard’s default settings. The second problem was that the chip experienced extreme, sudden temperature spikes that were causing my CPU fan to go insane, again while idling.

“Optimized Defaults” Aren’t

The i7-7700K has a reputation for running hotter than previous Intel offerings. This is absolutely true, but the degree to which “normal” temperatures for this chip have increased (pun intended) is exaggerated by the very poor default settings on many Z270 motherboards. The short version is that many Kaby Lake compatible motherboards – mine included – are overvolting the chips by default.

The stock turbo configuration my motherboard was using was 4.5 GHz with 1.345v. That is way too much voltage. Using those settings, I was getting idle temperatures of around 40 degrees and temperatures of 100 degrees and higher under load. I was actually getting thermal throttling at stock speeds with water cooling!

Some manufacturers have released BIOS updates that address this problem, so I first tried updating my BIOS software from version 0801 to version 0906. Temperatures did improve like I’d hoped they would, but it turned out to be one of those ironic monkey’s paw wishes: temperatures were lower because the BIOS locked my processor to 800 MHz. Apparently this is a known issue that affects people who enable XMP profiles for their RAM. I rolled back to the older BIOS version and configured the overclocking settings manually.

Ultimately, I was able to achieve a stable 4.9 GHz overclock at just 1.300v, resulting in much saner temperatures (~30 degrees idle, ~60 degrees while gaming, ~80 degrees at 100% load). It’s the first time in my life that I’ve ever had temperatures decrease after overclocking. Insane!

The lesson here is that if you’re doing a Kaby Lake build, you need to play around with voltages even if you want to run at stock speeds.

Extreme Temperature Spikes Aren’t Normal

Many people have noticed that the i7-7700K will exhibit momentary temperature spikes of anywhere from 20-25 degrees. When these spikes occur, the CPU fan responds by increasing fan speeds. I have seen some people on enthusiast forums claim that this is expected behavior with Kaby Lake, but the reality is that Intel Customer Support has acknowledged that this is an issue and have a dedicated thread in their support forum for updates regarding a fix.

I have no idea whether this is a problem that can be solved with a software update or if it will require a massive RMA, but either way, the true fix has to come from Intel. I “solved” the annoying fan speed problem for myself by:

  • Switching from an air cooler to an AIO water cooler. I’ve found that the water cooler is able to respond to the temperature spikes without increasing the speed of the fans on the radiator, which means that I don’t have to listen to any sudden loud fan noise. Even though the water cooler is louder overall than a good air cooler would be, it’s consistently loud in a way that makes it white noise I can easily tune out.
  • Adjusting the fan curve for my chassis fans so that they’re slower to respond to temperature increases. Because the temperature spikes are so brief, the chassis fans don’t respond to them.

It will be interesting to see when and how Intel fixes this, or if they bother to fix it at all.

Closing Thoughts

Despite all the problems I had initially, I’m pleased with my new rig. This thing is screaming fast, even if it took some tweaking to keep the fans from screaming too.

If I were building a new PC today – and didn’t have the time pressure of a failing motherboard – I’d wait a few months to see how everything shakes out. A lot of the early issues Ryzen had seem to be getting fixed with software updates. Meanwhile, Intel claims to be researching a fix for the temperature spike issue with the i7-7700K.

And, hey, let’s pour one out for Sandy Bridge, which manages to be relevant and useful about 6 years after its release.