ASUS P8Z77-V Premium Review: A Bentley Among Motherboardsby Ian Cutress on August 13, 2012 10:30 AM EST
For this benchmark, we run CrystalDiskMark to determine the ideal sequential read and write speeds for the USB port using our 240 GB OCZ Vertex3 SSD with a SATA 6 Gbps to USB 3.0 converter. Then we transfer a set size of files from the SSD to the USB drive using DiskBench, which monitors the time taken to transfer. The files transferred are a 1.52 GB set of 2867 files across 320 folders – 95% of these files are small typical website files, and the rest (90% of the size) are the videos used in the Sorenson Squeeze test.
Our chipset USB testing shows the Premium in the top half of each of our graphs. Of particular note is the USB 3.0 copy test, where the Premium equals our best native USB 3.0 copy timings, and using ASUS' enhanced Turbo option on the native USB 3.0, we achieve even better performance. When attached to the ASMedia controller under UASP, the ASUS P8Z77-V Premium performs better than any other motherboard's default solution.
Also of note is our Thunderbolt result for our copy test, which comes in at 1.20 seconds. This result was erratic, sometimes going to three seconds or above. When we come to testing more Thunderbolt motherboards, we have a different copy test to probe differences between the implementations.
We also use CrystalDiskMark for SATA port testing on a C300 drive. The sequential test (incompressible data) is run at the 5 x 1000 MB level. This test probes the efficiency of the data delivery system between the chipset and the drive, or in the case of additional SATA ports provided by a third party controller, the efficiency between the controller, the chipset and the drive.
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. So 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, resulting in an empty audio buffer – this leads to characteristic audible pauses, pops and clicks. Having a bigger buffer and correctly implemented system drivers obviously helps in this regard. The DPC latency checker measures how much time is processing DPCs from driver invocation – the lower the value will result in better audio transfer at smaller buffer sizes. Results are measured in microseconds and taken as the peak latency while cycling through a series of short HD videos - under 500 microseconds usually gets the green light, but the lower the better.
Surprisingly our ASUS P8Z77-V Premium DPC test comes in at one of the highest Z77 motherboard results, double the 60 microseconds of the ASUS P8Z77-V Pro. However, the result is still under 200 microseconds, which gives it an excellent rating.