GA-X58A-UD5 Revision 2.0 the MOST in Depth Review/ Analysis

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The UD5 is one of the Gigabyte boards with “Unlocked Power”. Every 1366 board has to be VRD 11.1 compliant meaning that it has to incorporate vdroop, and has to be able to supply a dynamic current increase of 100amps from 45amps at idle to 145 amps at load, that is at max vid of 1.375v and full load, in this condition the processor would have a TDP of 130watts at 80% load. There are also 35 more amps that are needed to supply power to the Uncore part of the processor including qpi link, ddr3 memory, and the internal memory controller. The purpose for vdroop is to lower voltage while the dynamic current increase occurs so that the processor can still stay within thermal spec. Heat and work are calculated from the simple physics equation P=IV (power= voltage x amperage) so if you raise amperage you need to lower voltage to maintain processor integrity.
Another unique feature of the phases is that the system doesn’t need to use all 16 phases at once, it can use just as many as it needs, Gigabyte states that this prolongs the life of the phases.
What is great about these new x58 boards is that they use top notch components, including but not limited to low core energy loss ferrite core chokes (the shiny cubes that count 16 around the CPU area), solid electrolytic Japanese capacitors with 50k hours life, and low RSD mosfets. Everything gigabyte uses is top notch quality; they implement DrMOS Vishay made mosfet drivers for each stage. These mosfet drivers are the SiC769CD they can perform vcore switching at 1MHz, have integrated generation III mosfets and are DrMOS compliant. They are pretty famous too.


At 90% efficiency each phase will change 12v of power from your PSU to 1.2v - 1.9v for the processor at 20-35amps at 1MHz. Totally wattage per phase is calculated from P=IV (power = voltage x amperage) so about 24-66.5 watts per phase, and that is still at 85%-90+% efficiency, those numbers are outstanding, these mosfet drivers are very capable, even at 8 phases you will be able to provide 192 watts of 1.2v power to the processor, but with the UD5 rev 2.0 you get double that so 384 watts! That is the least amount of power output from these phases. If we drop efficiency to 85% each phase can produce 32amps of power at maximum processor voltage of 1.9v @1MHz frequency, for an outstanding 972 watts available for the processor. Dropping efficiency lower would yield even more power, but you do stress out the mosfets, they generate more heat, and don’t live as long. You want to be around 85- 90+% efficiency so the voltage is stable and heat generated is below 100c. But these mosfets can take 150C operating temperature until thermal shutdown occurs, and at 135C the red flag is removed, and actually perform best from 20C-50C and then efficiency slowly declines.

A i7 900 series processor at 4.5-5.0 ghz wouldn’t even need 300 watts of power, but you are safe with over 900 watts at 85% efficiency which is just phenomenal, at 90% efficiency which is hard to take lower because power demand won’t surpass power delivery. Each phase in theory can provide 35 amps at 1.9v which would be the maximum. These phases do not operate on their own; they have their own controller and a very capable one at that. Gigabyte uses an Interstill Phase Buck PWN controller for these 16 phases, the ISL6336G, the UD9 has 2x ISL6336G.


What is special about this chip is that it allows you to run as many phases as needed, as low as 2 phases up to 16, but uses 8 phases at a time for normal operation this is possible because of a seperate iTE phase switching chip in the Random IC section. The PWN controller is responsible for providing input voltage of 12v to each phase. The added benefit of this array and the integrated mosfet drivers along with the ferrite choke cores is that you are able to centralize and more effectively control the different stages of voltage delivery as well as the overall array allowing lower thermal output and a perfect CPU power delivery design, this PWN controller also reduces input and output voltage ripple by monitoring current and resistance along the load line and making proper adjustments, while monitoring and protecting the system with over current protection/over voltage protection.


Now let’s move on to the X58 chipset power, the X58 chipset has its own 4-phase PWN buck controller with 4 additional low RSD mosfets that are cooled by a tiny heatsink not attached to the CPU phases. There are also 4 ferrite core chokes. The buck controller is the Interstill ISL6312.

This layout is a mini version of the power delivery system for the processor. The ram has its own double phase PWN (this PWN is also designed to use 3 phase design), the Interstill ISL6322G, as well as 3 ferrite core chokes and 4 low RSD mosfets an even smaller version of the processor power array.



Note: What you should also consider is that the processor feeds power directly to the DDR3 memory as well. To sum up the power delivery of the board, it’s just phenomenal, for the price you pay this board really delivers.
All of this power generates heat that needs to be dealt with, Gigabyte did not leave you high and dry, they left you something cool and quiet.