Borrowing big brother's firmware
While Asus' hardware engineers may have built the Z97-P as a budget board, happily for the consumer, no one told the firmware team.
Upon entering the UEFI, we're greeted by the same duo of EZ and Advanced interfaces found on Asus' higher-end boards. The excellent fan speed controls are carried over largely intact, as is the change log of config options on exit. Rather than rehashing what Geoff has already covered in his Z97-A review, I'll instead concentrate on where the Z97-P differs.
Some firmware elements rely on hardware functionality built into the board. On the Z97-P, there's a subtle reduction in the flexibility of the fan speed controls. Whereas individual fan profiles can be linked to one of four different temperature sensors on the Z97-A, the Z97-P only has two sensors: CPU and motherboard. This minor difference isn't worth quibbling over for a budget board, but it's worth noting, because we'll see a similar hardware-dependent difference when we tackle automatic overclocking.
business suit software
The memo that the firmware folks missed about the Z97-P being a budget board also didn't make its way to the software department, because Asus' excellent AI Suite tweaking utility trickles down to the lowest ranks of the Z97 lineup. Perhaps both teams blew off the same meeting? In any case, the Z97-P reaps the rewards.
The vast majority of AI Suite on the Z97-P is the same as users would experience on Asus' other Z97 boards. Once again, I'll point you to the coverage in our Z97-A review. One difference is found in the auto-overclocking section. Instead of going through an iterative process of slowly raising the clock speed, checking stability, and rinsing and repeating, the TurboV auto-tuner instead selects speeds based on pre-defined profiles. Users can only choose whether to target the CPU multiplier exclusively or boost the base clock first.
The software auto-clocker mirrors the functionality of the OC Tuner firmware option. Both are bound by the board's lack of a TPU, or TurboV Processing Unit, which is the brains behind Asus' more sophisticated iterative tuning method. Novice system builders and first-time overclockers are losing valuable functionality here.
The firmware and software are both rich with manual overclocking controls, so seasoned overclockers shouldn't be fazed by the profile-based auto tuner. The Fan Xpert software remains full-featured, as well, giving users complete control over the thermal and noise profiles of their systems.
It's also worth pointing out that the Z97-P's AI Suite is missing the Turbo App component. Turbo App lets users associate performance profiles with individual executables, like specific games or applications.
When Haswell chips first showed up in the market, unfettered overclocking was strictly the domain of K-series parts, the cheapest of which started at $242. Little had changed from previous Ivy and Sandy Bridge generations. Then, roughly a year later, Intel celebrated twenty years of the Pentium brand by releasing a cheap, completely unlocked dual core processor—the Pentium Anniversary Edition, or G3258. Suddenly, unrestricted overclocking could be had for $72 or even less.
Since a CPU's overclocking prowess can vary from chip to chip, the silicon lottery tends to determine the top stable speed more than one's choice of motherboard. Still, whether your particular CPU is the golden child of the wafer or the runt of the litter, you want a motherboard that makes the process of finding out as painless as possible.
With all of this in mind, we put the Z97-P through its overclocking paces. Our companions on the journey were a retail Pentium AE chip and a Cooler Master Nepton 240M closed-loop liquid cooler. The Nepton has a double-length radiator and $130 price tag, making for an unlikely marriage with the budget CPU. However, we can at least be assured that thermals didn't hold back our overclock.
Our first stop on the road to peak clock speeds was the firmware's EZ Tuning Wizard. After confirming that we had a liquid cooler and that our purpose in life was to play games and encode media, the wizard bestowed a 45X multiplier and 102MHz base clock. To achieve the resulting 4.6GHz clock speed, the firmware supplied the CPU with 1.375V. Unfortunately, our little chip wasn't happy under such conditions, and it steadfastly refused to enter Windows. At least the wizard warned us that instability could ensue.
Next, we tried the auto-tuning feature in AI Suite. After activating ratio-only mode and rebooting, we found the CPU multiplier raised to 36X with the voltage at its default value. This config proved completely stable. A quick trip back to the auto-tuner—this time to focus its attention on the base clock—left us with a final frequency of just over 3.7GHz thanks to a 103MHz base clock. This setup was also stable, with no thermal throttling detected.
With the automated options giving us aggressive and conservative attempts, it was time to see what we could do with the firmware's manual controls. Using multiplier tweaking alone, with the voltages on their "auto" defaults, we made it all the way to 4.3GHz while maintaining stability. At this speed, the firmware supplied 1.277V to the CPU, and temperatures maxed out at 67ºC under a Prime95 load.
To reach a stable 4.4GHz, we had to switch to manual voltage tuning. The firmware-supplied 1.325V wasn't enough to keep Prime95 from causing reboots, but 1.35V allowed stable operation. Temperatures hovered at or below 70°C under load, and there was no evidence of throttling.
Not content with an overclock of less than 40%, we pressed on. Stability at 4.5GHz was achieved, but at an increased voltage of 1.425V. Temperatures peaked at 77°C, and so did the noise produced by the Nepton's fans. That's where our journey ended, unfortunately. We achieved our goal of a 40% overclock, but no amount of voltage allowed Prime95 to run without causing reboots at 4.6GHz, even with temperatures under 84°C.
Although we didn't reach the oh-so-magical milestone of a 50% overclock, Asus' excellent UEFI made getting to 4.5GHz a pleasant experience. We couldn't get the same CPU-and-cooler combo running any faster on the Gigabyte Z97-HD3, a comparable Z97 board we'll be reviewing soon, so it's probably safe to assume the Z97-P pushed our particular slice of Haswell silicon to its limits.