vvoid said: AlphaC, may I ask you what you think about Gigabyte's Aorus ranking. I mean, why is the Master considered a higher tier VRM-wise? Ok, it has IR components, but on the other hands its IR3553 power stages are only 40A each, compared to 50A for the SIC634 on Ultra/Pro/Elite. Also, Ultra/Pro/Elite's doublers (ISL6617) seem more intelligent being able to actively power balance and not just blindly interleave phases, like the IR3599 on Master. So on paper, Ultra/Pro/Elite do look superior to Master VRM-wise, what am I missing? Click to expand...

a lot

* For a competitive comparison, the ROG Hero is using 8 of those SiC639 , which would be just under 2.5W per phase in heat production. 2.5W x 8 = 20W

* Also a competitive comparison to the Taichi, 10x TI CSD87350 is around 2.6W per phase (~19A per phase) not including drivers, 2.6x10 = 26W and thermal resistance is higher at 20°C/W junction to mosfet casing



I actually thought about this before the Intel i9 spec was released , it was a concern I relayed to Matt earlier in this thread (i.e. why did R&D spend double and dump money).IMO Gigabyte's R&D department needed to reevaluate their boards' bill of materials and maybe they still do. They dumped $7 ISL Smart powerstages and 70A Cooper Bussman R15 chokes into their $200 Gaming 7 for hexcores and then manage to screw up the VRM heatsink with RGB and extremely low fin area. That was compounded by some Z370 Gaming 7 boards having poor thermal pad contact and without a BIOS switch there was no outright superiority to z370 Taichi in that aspect when you account for 138A recommended current maximum for i7 hexcores. Their Z370 midrange was basically their lowest z370 boards with more RGB / audio upgrades and an extra high side fet + drivers. With Z390 they've donebetter with this, the VRM heatsink is well finned on the Master/Ultra despite having RGB under-lighting and the cost of the VRM is lower by nearly half on the Master board compared to Z370 G7. Gigabyte's design change has been the polar opposite of MSI's: MSI has been using close to the cheapest mosfets (~$0.25-0.30 each or around $0.50 to $0.60 per phase if doublers aren't used) for the CPU V_Core and dumping R&D money into memory optimization.The Gigabyte z390 Aorus Master has overclocking features such as the voltage readout points , BIOS socket-able chip, power/reset/clear CMOS, and the BIOS switch (the dual BIOS on the other boards don't have the switch) compared to the Ultra. Much money they spent in R&D was dumped into the audio (ESS DAC , etc), cooling, RGB (the VRM heatsink change was a nice touch as I've stated before), and other stuff as well.Unless you push more than 200A into the CPU (Intel spec is 193A max for octocore i9) it is probably within margin of error for the Master & Ultra with heatsinks.193A over 12 phases is around 16A per phase. At 16A per phase you're looking at around 1.7W per phase that needs to be dissipated per IR3553 (>92% efficiency per graph) , which is just over 20W for the VRM heatsink and thermal backplate to handle. As long as it has a 150nH inductor or more it will have this much power loss or less.For the SiC634 that's around 1.2W per phase per Figure 10 , around 15W total for the VRM heatsink to dissipate. Somehow it's stated as ~92% efficient at ~15A (but that's with 1V output). We don't have access to a voltage scaling graph or inductor scaling. From the graph of the SiC620 performance in the VRPower pdf I would think it is within 1% efficiency difference.However, since the Master has a massively increased surface area and a thermal backplate the board will be likely be cooler in practice. If you look at the datasheet for the IR3553, thermal resistance into the PCB is lower than to the casing (2.5 °C/W into PCB while 23.2 °C/W to casing). At lower loads with fixed voltage the Master might have a higher peak efficiency due to the SiC634 datasheet being normalized for 1V. The factor for IR3553 is 1.05X from the 1.2V standard to ~1.3V and 1.1X at 1.4V. Power loss vs switching frequency has fairly minimal difference unless you push over 600kHz (