Our first attempt at overclocking one of Intel’s new “Devil’s Canyon” processors was, frankly, a little bit underwhelming. Intel had pitched these new processors as especially good for high clock speeds, thanks to some changes to the heat-transfer and power-delivery bits in the CPU package, but we couldn’t get our Core i7-4790K review sample to run any faster than a regular Haswell-based 4770K. Many others in the press saw similar results. We liked other things about Devil’s Canyon, such as the 4790K’s higher stock clock speeds at the same price as the 4770K, but its overclocking prowess just didn’t impress.
Then, frustratingly, we heard whispers from one vocal Intel employee who suggested that final, production versions of Devil’s Canyon might perform better. I’ve gotta say, as a reviewer, I’m not fond of that entire concept. My great hope and expectation is that whatever chip we’re reviewing is pretty well representative of what people will be buying soon.
But whatever. Maybe, in this case, it was true. Maybe there would be something different about the chips that hit store shelves. There is, of course, one simple way to find out.
That’s why I was particularly receptive when the folks at MSI extended a tantalizing offer: let us send you a retail version of the Core i7-4790K along with one of our fancy Z97 MPower motherboards. You can overclock it and see how it goes.
Well, okay, then. Seems like it’s worth a shot.
We’re just looking at a single sample of a retail Core i7-4790K, so we’re not exactly doing science to this thing. Whether or not our results will track with your own, should you buy a 4790K, is pretty much anyone’s guess.
Heck, I didn’t expect this, but MSI shipped the Core i7-4790K to us in the box with the Z97 MPower motherboard, covered in nothing but bubble wrap. I was somehow expecting a retail boxed processor, with the ain’t-been-opened stickers still intact. Perhaps I should have mentioned that to them. The markings on the CPU’s metal cap indicate a final product, but for all I know, MSI went through a big stack of 4790K chips and sent only the most frequency-friendly examples to guys like me. So caveat your emptors, folks. Who knows what any of this means.
I’ve got the MPower
I was happy to see the Z97 MPower make its way into Damage Labs. At $185 online, this is the sort of high-end board that, frankly, we’ve kind of avoided at times here at TR, simply because we’re ridiculously frugal and tend to focus our reviews on cheaper boards where possible. The Z97 MPower is part of MSI’s overclocking-centric motherboard series, and you’ll pay a bit more to get its suite of extra-fancy features.
I’ve gotta admit, some of the perks are nice, not least of which is the look of the board itself. The MPower may be the handsomest motherboard ever to grace Damage Labs with its presence. Many of the premium features of the MPower’s spec sheet are incredibly nebulous things like “enhanced components” and “OC certified” that don’t make a lot of sense to me. (Who does this OC certification? Is there a board with strict criteria? Somehow, I doubt it.) Still, MSI has included some obvious nods to hard-core overclockers, like the row of multimeter-ready voltage-check terminals next to the ATX power connector and the ability to clock DDR3 DIMMs at speeds up to 3300 MT/s.
And, hey, this is just a really nice Z97 mobo, with a slot for M.2 SSDs and a gaggle of SATA 6Gbps and USB 3.0 ports.
The Z97 MPower’s firmware interface is very similar to the one in MSI’s Z97 Gaming 7 board that Geoff reviewed not long ago. You’ll find everything you need there to make an Intel processor do unnatural things with its clock frequencies, and the interface itself looks as pretty as, you know, motherboard firmware can probably get.
I have to admit that I struggled to find a few settings every now and then, in part because I’ve spent more time recently with boards from Gigabyte and Asus. MSI has made some nice progress on its firmware, but the organization is a little different. For instance, the pane on the right side of the main menu where one can access the fan-speed controller disappears entirely once you start modifying something else, like CPU voltage. To get it back, you have to press the Escape key one more time than my instincts tell me should be necessary. Once you find the appropriate menu, though, the fan-control interface is slick and capable.
I did run into a few honest-to-goodness rough edges with the MPower board, too. For one thing, the CPU fan headers on this mobo only support PWM-style four-pin fans, a fact that isn’t spelled out terribly prominently in MSI’s documentation. The DC fan on my Thermaltake NIC C5 cooler acted strangely, and I couldn’t sort out the problem until I happened to mention it to Geoff. He quickly explained that he’d run into the PWM limitation on some of MSI’s other boards, and I instantly knew what was up. If you don’t retain a Geoff on staff like I do, sorting out this problem may take you longer.
Fortunately, the MPower’s system fan headers do support DC-style fans, and their speed-control settings can be set to key off of CPU temperatures. In seconds, I had the NIC C5’s fan ramping up and down smoothly in response to CPU temperatures.
In search of higher frequencies
These days, amazingly enough, motherboards will overclock your processor for you. I’ve been aware of this fact for a while, especially since Geoff has been testing auto-overclocking features in motherboard reviews, but I’ve never actually bothered to try them. Not for years, at least, since those features were in their infancy and didn’t do an especially good job.
You see, I have mad skillz involving multiplier and core voltage settings. I can change both variables at once in the BIOS, yo. F10 and it’s on, friend.
But I figured this time around, I’d give MSI’s OC Genie button a try. Seems like a gimmick, putting a push-button right on the motherboard itself that says “overclock this thing,” but the actual concept appears to be sound in theory. MSI maintains a set of profiles for common CPUs and will invoke a fitting profile when you press the OC Genie button. What you’ll get probably won’t be the highest possible speed for your processor, but it should be a reasonably decent overclock with a high probability of success. Why not start there?
I hit the OC Genie button, powered on the system, and BAM! Error message. Overclocking failed. Press F1 for the BIOS menu and whatever.
I made several more attempts, but no dice. The board threw an error every time I tried to boot with OC Genie enabled. I’m not sure what exactly the problem was, because this feature is kind of a black box. Were the memory timings too aggressive? Did it need a little more CPU voltage? Impossible to say.
Being the curmudgeon that I am, I brushed off this problem with a shrug and went to work in the firmware menus myself. Who needs a genie, anyhow? I’ve got this.
To be clear, what I’ve got is a really simple approach to overclocking an unlocked CPU: strap on a big-ass tower cooler, crank up the multiplier to something plausible, and raise the CPU core voltage as needed. Repeat the mult and voltage tweaks until something breaks.
With a little coaxing, I was able to get the retail Core i7-4790K running and reasonably stable at 4.8GHz and 1.32V.
I tried for 4.9GHz, and the chip was able to boot into Windows at that speed, but it quickly crashed when I started up our Prime95 load test. I tried raising the voltage in steps, going as high as 1.424V, but the chip just wasn’t happy at that clock speed.
4.8GHz at 1.32V ain’t bad. We were able to benchmark our pre-release sample of the 4790K at 4.7GHz, but it needed 1.45V to get there, which is quite a bit of juice for a 22-nm processor. And that earlier 4790K was a little iffy at 4.7GHz. Given everything, I’d call this retail chip 200MHz better, if you’re looking for a realistic overclock for long-term use. (Those retail CPU voltages, by the way, come from MSI’s monitoring software. I found that if you asked the board for 1.3V in the firmware, you’d get 1.32V. Ask for 1.35V, you get 1.368V. And so on. It errs on the side of more juice, which is a little scary when you’re hitting the limits of your chip or cooler.)
That clock speed improvement isn’t gonna set the world on fire, and this one sample isn’t enough to establish any sort of a trend. Still, every data point we’ve seen points to something in the range of 4.7 to 4.8GHz being the most common limit for a Devil’s Canyon CPU—which is awfully similar to a regular Haswell K-series part.
And, you know, it’s really fast.
With the retail CPU at 4.8GHz and running Prime95, our Z97 MPower-based test rig drew about 210W under load at the wall socket. CPU temperatures peaked at about 80°C. The system’s power use dropped down to about 54W at idle on the Windows desktop, which is almost exactly what Geoff saw from the Z97 Gaming 7 with a stock-clocked, default-voltage processor.
It may well be possible to squeeze even higher clock speeds out of a Devil’s Canyon CPU with extreme cooling and the like, but that is a question for the dudes with liquid helium pots. I am not one of those dudes.