GPUs Hardware Reviews

Reason instead of obesity: Gigabyte RX Vega64 Gaming OC in test

If there were enough Vega chips and thus a wide range of cards, the Gigabyte RX Vega64 in this form would probably be the ideal entry-level card, rather than a top-of-the-line model. But it really must always be the demonstration of what is technically feasible... Board layout As with the RX Vega56 Gaming OC, Gigabyte is extremely different from AMD's reference layout, which should also make the use of existing full-cover water coolers impossible. Also at the popular Raijintek Morpheus, the end of G... We have to put it in the first place that we actually had to double-benchmark all the games. At the last moment, Gigabyte incorporated AMD's new kernel from the source BIOS, which accommodates the custom models with a customized power table. D... Power consumption at different loads The power consumption in the gaming loop is at the measured approx. 261 watts in Balanced Mode about 20 watts below what could be measured at the reference in the default BIOS. This is all the more astonishing because... Overclocking and undervolting The conventional overclocking by means of an even higher power limit and more clock counteracts the current cooling concept, because the rather quiet cooler gets along quite well with what it has to dismount ex works. More on the other hand... Cooling system and backplate Of course, the generated waste heat is directly related to the recorded power, for which the cooling solution is responsible for optimum dissipation. And this is precisely where we are faced with various compromises, which are... Summary For the Gigabyte RX Vega56 Gaming OC we have already written a very detailed conclusion, which applies unreservedly to the bigger sister in the same forum. Butter-and-bread instead of lighthouse project and cost optimization for ...

Board layout

As with the RX Vega56 Gaming OC, Gigabyte is extremely different from AMD's reference layout, which should also make the use of existing full-cover water coolers impossible. Also with the popular Raijintek Morpheus, end terrain is terrain, if you take a closer look at the voltage converter positioning for the GPU (VDDC).

Gigabyte also uses 6 phases with Doubling for the big sister, resulting in a total of 12 voltage converters for the VDDC and one phase for memory (MVDD), but their positioning for third-party coolers poses real problems. The production of the further auxiliary voltages is also shown in the diagram.

If you look at the back of the board, you can see that half of the most loaded low-side MOSFETS have gone right there. From this it can now be concluded that more than 30% of all voltage transformer losses occur, including the associated waste heat, on the back.

The whole thing can definitely no longer be removed cleanly from the front, but also requires a special cooling solution for the back. How Gigabyte solves this, we will see later and also test it.

Gigabyte relies on a total of two external 8-pin jacks. Since the motherboard slot is about 25 watts maximum, these two connections must therefore handle the rest. We'll see how much that is later.

In general, however, it has been noticed that gigabytes are many things that we still have on the development pattern or the reference board, has simply omitted it here. This starts with the Holtek microprocessor for RGB control (you can hurt) and ends with the dual BIOS (already more annoying). In the end, everything looks a bit like the savings version of a formerly quite ambitious project.

GPU Power Supply (VDDC)

As with the reference design, the focus is on the IR35217 from International Rectifier, a dual output digital multi-phase controller that can provide both the six phases for the GPU and a wider phase for memory, which we are about to will come to speak. But back to the GPU and thus to what we see in the schema above as a VDDC block. We count 12 voltage transformer circuits, not six. However, since only six real phases are created, you double each of these phases in order to be able to divide the load into two converter circles per phase.

 

 

A total of six IR3598s are used for this so-called doubling, half of which are located on the front and back of the board. The actual voltage conversion of each of the 12 converter circuits is carried out by one AON6594 on the high and two parallel AON6360 on the low-side (all from Alpha & Omega). This is a favorable but acceptable component choice, especially since the parallel connection can also flatten the thermal hotspots.

 

 

For the coils, Gigabyte relies on Magic Chokes from Foxconn for both the VDDC and MVDD range. With only 10nH for the VDCC, however, these encapsulated ferrite core coils are rather small. The coils for the one MVDD phase are on average at 22nH, even if 33nH has been sighted here often enough.

 

 

Power supply of the memory (MVDD)

As mentioned briefly, the IR35217 also provides one phase for storage. One phase is sufficient for the card, as the memory is much more sufficient. As with the VDDC, one relies on an AON6594 on the high side and two parallel AON6360 on the low-side (all from Alpha & Omega).

 

 

Other voltage converters

The creation of VDDCI (pictured bottom left) is not a big item in terms of performance, but it is important. It is used for GPU-internal level transition between the GPU and memory signals, something like the voltage between the memory and the GPU core on the I/O bus. In addition, a constant source for 0.9 volts is generated (picture at the bottom right). These two very similar voltage converters each rely on an asymmetric dual-N-channel MOSFET AON6994 from Alpha & Omega.

 

 

In addition, there is also a 1.8V source (TTL, GPU GPIO, image at the bottom left) on the front side, which is identically equipped with an AON6994. Below the GPU you can still find the APL5620 from Anpec for the VPP. This ultra-low dropout chip generates the very low voltage for the PLL area (Phase Locked Loop, image at the bottom right).

 

 

So we would almost be through, because the rest is the usual standard. Only the stand-alone BIOS chips 25Q4, which is a simple SPI flash chip, are still striking. Gigabyte has simply saved the switch, as well as the second BIOS chip, even though it is provided on the board (and thus possible).

In the entrance area there is a ferrite core coil with 68 nH for the input filtering, which helps to block the occurring load peaks including the incidental products of power supply.

 

 

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About the author

Igor Wallossek

Editor-in-chief and name-giver of igor'sLAB as the content successor of Tom's Hardware Germany, whose license was returned in June 2019 in order to better meet the qualitative demands of web content and challenges of new media such as YouTube with its own channel.

Computer nerd since 1983, audio freak since 1979 and pretty much open to anything with a plug or battery for over 50 years.

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