The ASRock Z370 Gaming-ITX/ac Motherboard Review: Mini-ITX with Thunderbolt 3

System Performance

Not all motherboards are created equal. On the face of it, they should all perform the same and differ only in the functionality they provide - however, this is not the case. The obvious pointers are power consumption, but also the ability for the manufacturer to optimize USB speed, audio quality (based on audio codec), POST time and latency. This can come down to manufacturing process and prowess, so these are tested.

Power Consumption

Power consumption was tested on the system while in a single GPU configuration with a wall meter connected to the Corsair HX 750 power supply. This power supply is Platinum rated. As I am in the US on a 120 V supply, leads to ~87% efficiency > 75W, and 92%+ efficiency at 375W, suitable for both idle and multi-GPU loading. This method of power reading allows us to compare the power management of the UEFI and the board to supply components with power under load, and includes typical PSU losses due to efficiency. These are the real world values that consumers may expect from a typical system (minus the monitor) using this motherboard.

While this method for power measurement may not be ideal, and you feel these numbers are not representative due to the high wattage power supply being used (we use the same PSU to remain consistent over a series of reviews, and the fact that some boards on our test bed get tested with three or four high powered GPUs), the important point to take away is the relationship between the numbers. These boards are all under the same conditions, and thus the differences between them should be easy to spot.

Power use on the ASRock Z370 Gaming ITX/ac is very good, with it leaning towards the more efficient side of things here. Idle power use was 38W for long and 43W for OS idle while load results were 131W - the best result of any Z370 board. 

Non-UEFI POST Time

Different motherboards have different POST sequences before an operating system is initialized. A lot of this is dependent on the board itself, and POST boot time is determined by the controllers on board (and the sequence of how those extras are organized). As part of our testing, we look at the POST Boot Time using a stopwatch. This is the time from pressing the ON button on the computer to when Windows 10 starts loading. (We discount Windows loading as it is highly variable given Windows specific features.

The POST times for this board were the fastest we have seen yet at 17.9 seconds default and 16.8 seconds stripped. This beats out the B360/H370 boards that held the crown previously. 

DPC Latency

Deferred Procedure Call latency is a way in which Windows handles interrupt servicing. In order to wait for a processor to acknowledge the request, the system will queue all interrupt requests by priority. Critical interrupts will be handled as soon as possible, whereas lesser priority requests such as audio will be further down the line. If the audio device requires data, it will have to wait until the request is processed before the buffer is filled.

If the device drivers of higher priority components in a system are poorly implemented, this can cause delays in request scheduling and process time. This can lead to an empty audio buffer and characteristic audible pauses, pops and clicks. The DPC latency checker measures how much time is taken processing DPCs from driver invocation. The lower the value will result in better audio transfer at smaller buffer sizes. Results are measured in microseconds. 

Our DPC latency results for the Z370 Gaming ITX/ac reached 265µs which is actually the best result we have seen so far in an Z370 based motherboard. We did not experience any issues with audio in our time with the board.