RX Vega 56: Laptop versus Server

AMD’s RX Vega 56¬†GPU is good for more than just cryptocurrency mining. It can produce impressive visuals and high frame rates in the latest PC games when used in an appropriate gaming PC with at least 16 GB RAM and a 4 GHz multi-core CPU like the i7-8700K or Ryzen 7 1700X.

Instead, I’m going to see how well it performs in two inappropriate systems: an ultra-portable laptop, and a dual-socket rack server.

Dell’s Precision Rack 7910 is a built-to-order 2U rack server. This unit came with Dual Intel Xeon E5-2683 v4 CPUs up to 2.8 GHz, 256GB DDR4 RAM, empty slots for two full-size GPUs and a single 1100W power supply providing two sets of 8-pin plus 6-pin GPU power connectors.

2 CPUs, 32 cores, 64 threads.

The Vega 56 GPU has been flashed with firmware from a Vega 64 bringing the core speed up to 1.6 GHz with memory at 945 MHz. The power limit and fan speed were both increased to maximum.

The reference cooler on RX Vega resembles a hair dryer.

For comparison I wanted to test the Vega GPU with an AMD FX 8350 4GHz 8-core CPU. AMD recommends a newer motherboard with PCIe 3.0 and UEFI – which usually wouldn’t matter because GPUs are mostly backwards-compatible with older features – but in this case Windows 10 always crashes while initiating the Radeon driver.

Does not work.

Instead I’ll compare Vega’s performance in the PR 7910 against my laptop, a Dell XPS 13 9350 with Intel i7-6560U CPU up to 3.1 GHz, 8GB DDR3 RAM, Intel Iris 540 GPU, and an AKiTiO Node Thunderbolt 3 external GPU enclosure (with upgraded power supply) for connecting the GPU. The thermal compound on the CPU has been replaced, extra thermal transfer pads were added, and the CPU was undervolted to eliminate power and thermal throttling.

1 CPU, 2 cores, 4 threads.

The XPS 13 will be tested in three configurations:

  1. Intel Iris 540 GPU with the laptop’s internal display.
  2. AMD Vega 56 GPU with the laptop’s internal display.
  3. AMD Vega 56 GPU with external display connected to the GPU.

All tests will be conducted in 64-bit Windows 10 Pro version 10.0.15063. Game benchmarks are set to the highest visual quality at 1920×1080 (1080p) and 3200×1800 (1800p). A score of zero means the test crashed or refused to launch.

Tomb Raider

Batman: Arkham Knight

Ashes of the Singularity

Deus Ex: Mankind Divided

Rise of the Tomb Raider

Tomb Raider (2013) and Deus Ex: Mankind Divided refused to run on the PR 7910 server. Ashes of the Singularity and The Talos Principle were unable to use the external GPU with the XPS 13’s internal display, but worked when I connected a display to the GPU.

The external GPU on the XPS 13 performed worse when it had to send frame data back into the laptop’s internal display. There seems to be an upper limit of around 80 frames per second at 1080p and 40 at 1800p due to bandwidth constraints on the Thunderbolt 3 cable.

The XPS 13 beat the PR 7910 in only three tests: The Talos Principle (Vulkan 1080p), Ashes of the Singularity (DX11 1800p) and Fire Strike (Graphics). The laptop’s faster CPU speed may have given it the advantage in these specific workloads.

Fire Strike (Physics) and Time Spy (CPU) showed a massive difference between the XPS 13’s dual-core CPU and the PR 7910’s pair of 16-core CPUs. Rise of the Tomb Raider also performed significantly better in the PR 7910 thanks to more CPU cores and more RAM.

The truth is that neither of these systems are ideal for gaming. They both have relatively slow CPU speed and cannot be overclocked to improve it. The PR 7910 is built for highly-parallel scientific computation with lots of CPU threads. The XPS 13 is optimised for low power consumption to improve battery life, and is also handicapped by only 8 GB RAM when many games now require more than that to run smoothly.