New video cards are coming out furiously and bringing with them new manufacturing processes and better price-to-performance ratios.

One of newest memory technologies on the market is HBM (High Bandwidth Memory), introduced on the R9 Fury X. HBM stacks 4 memory dies atop an interposer (packaged on the substrate) to get higher density modules, while also bringing down power consumption and reducing physical transaction distance. HBM is not located on the GPU die itself, but is on the GPU package – much closer than PCB-bound GDDR5/5X memory modules.

Benchmarking in Vulkan or Dx12 is still a bit of a pain in the NAS, but PresentMon makes it possible to conduct accurate FPS and frametime tests without reliance upon FRAPS. July 11 marks DOOM's introduction of the Vulkan API in addition to its existing OpenGL 4.3/4.5 programming interfaces. Between the nVidia and AMD press events the last few months, we've seen id Software surface a few times to talk big about their Vulkan integration – but it's taken a while to finalize.

As we're in the midst of GTX 1060 benchmarking and other ongoing hardware reviews, this article is being kept short. Our test passes look only at the RX 480, GTX 1080, and GTX 970, so we're strictly looking at scalability on the new Polaris and Pascal architectures. The GTX 970 was thrown-in to see if there are noteworthy improvements for Vulkan when moving from Maxwell to Pascal.

This test is not meant to show if one video card is “better” than another (as our original Doom benchmark did), but is instead meant to show OpenGL → Vulkan scaling within a single card and architecture. Note that, as with any game, Doom is indicative only of performance and scaling within Doom. The results in other Vulkan games, like the Talos Principle, will not necessarily mirror these. The new APIs are complex enough that developers must carefully implement them (Vulkan or Dx12) to best exploit the low-level access. We spoke about this with Chris Roberts a while back, who offered up this relevant quote:

The only widespread implementation of Vulkan that presently exists is The Talos Principle, which offers both the Vulkan and DirectX 11 APIs. We've mostly seen negative scaling in the Talos Principle when switching to Vulkan, but id Software's DOOM promises gains in framerate by switching from OpenGL (4.3 & 4.5) to Vulkan.

AMD's panoply of RX 480 news announcements teased superior performance to the then-new GTX 1080 when paired in CrossFire. We decided to buy a second RX 480 8GB card for $240, put it into CrossFire with our sample that we reviewed, and validate those claims.

Multi-GPU configurations are tough to benchmark. We need to perform all the same thermal, noise, power, and FPS analysis as with other devices – but special attention must be paid to 1% and 0.1% low frame values, and more attention still paid toward plotting metrics versus time. Frequency, temperature, and fan RPM have some fluctuations that appear with multi-GPU configurations which are only truly visible when plotting versus time, rather than averaging a set of thousands of points of data.

In our performance review of CrossFire RX 480 8GB cards, we test FPS in Mirror's Edge, The Division, GTA V, and more, alongside temperature, noise, and power performance. We understand that thermals, noise, and power are sometimes less exciting to readers than raw FPS output, but would strongly recommend looking into our results for this benchmark – multi-GPU setups put greater emphasis on such testing. Some games show negative scaling, some positive, and some which are nearly unchanged. All of that below.

Before proceeding: This endeavor is entirely at the risk of the user, and there is a possibility of “bricking” or permanently damaging the hardware during this process.

In 4GB vs. 8GB AMD RX 480 benchmarking, our testing uncovered improvement in just a few titles – but the improvements were substantial when present. It is no mystery that early press samples of the card allowed for flashing to 4GB, which resulted in a 1750MHz memory clock and locked 4GB of the VRAM. This is reasonable, as media obviously wanted to test both versions of the card, but AMD wanted to limit sampling. We actually liked the way this was handled, given the option between a flashable sample and strictly an 8GB sample.

But there's more to it than that: Consumers have reported success flashing VBIOS from sold 4GB retail samples, resulting in 8GB cards. Let's talk about why AMD's shipping of “locked” cards makes sense, risks, and how to perform the procedure.

We've already had hands-on experience testing AMD's new 16.7.1 driver update, following the 16.6.2 release with the RX 480 cards. Our testing instituted an early beta version of the driver for our 4GB vs. 8GB RX 480 benchmark, which showed that initially reported GTA V stuttering issues have since been resolved.

Unknown to us at the time of the 4GB vs. 8GB benchmark, the 16.7.1 update also aims to resolve some of the PCIe bus power draw concerns. AMD's pre-weekend statement indicated an update on July 5, which was released as below:

Multi-SKU launches of GPUs are sort of interesting. The RX 480 ships in 4GB and 8GB models, with some other less-than-obvious differences under the hood. GDDR5 speed, for instance, operates at 7Gbps on the reference 4GB model, as opposed to 8Gbps on the reference 8GB model (which we reviewed in great detail). There's potential for confusion in the marketplace with multiple SKUs, and the value proposition gets muddied between the $200 4GB RX 480 and the $240 8GB RX 480. That's not counting AIB partner cards, either, and those are rolling out.

In this benchmark, we compare the RX 480 4GB vs. RX 480 8GB to determine if the difference is "worth it" in games. We're testing GTA V, Assassin's Creed, Call of Duty, Shadow of Mordor, Ashes, and more.

For a previous look at VRAM differences, check our (now dated) GTX 960 2GB vs. 4GB comparison.

A few of the first AIB partner models of the AMD RX 480 were revealed last week, and should be hitting the market within the next few weeks. Following our recommendation to dodge the reference RX 480 design – except for in specific SFF use cases – the AIB partner cards promise better cooling minimally, or different power setups maximally.

Thus far, we've seen the Sapphire RX 480 Nitro (the company's “gamer” line), the ASUS RX 480 Strix, and the PowerColor PCS RX 480 Devil. Coolers have been revealed in most detail for the Nitro and Strix cards, detailed more below.

The AMD RX 480 “Hybrid” quest we embarked upon revealed some additional overclocking headroom, but also prompted a good opportunity to demonstrate live RX 480 overclocking. We've returned to showcase that today, alongside a top-level explanation of GPU core voltage, core frequency, fan RPM, power % target, and stability.

Note that there are a few disclaimers to be made with any type of overclocking: First, it's likely that any such endeavor voids the warranty, at least if exiting a range permissible by the AIB partner or OEM. That's because overvolting and power increases can potentially cause damage to chips long-term (or even immediately, if no restrictions are in place), and that's especially true on cards where cooling may not adequately cool critical components governing overclocking – like the MOSFETs and other VRM components. That's not to scare anyone away, though; overclocking is fairly safe if following basic rules of small, incremental stepping and using guides (and using OEM-provided software, which often has restrictions for safety). It's just that overclocking is always an “at your own risk” venture, and it doesn't hurt to remind everyone.

This guide explains how to use WattMan to overclock the AMD Radeon RX 480 GPU, showcases voltage (for overvoltage or undervoltage), power target, and some performance metrics.

AMD has issued a statement regarding purported issues with excessive power draw across the PCIe bus, resultant of a single, limiting 6-pin power header from the PSU. We are researching this issue independently and allocating resources to new power testing equipment. We also just purchased a retail RX 480 Reference card, which we will use to determine if the issue occurs on non-review products. So far, it seems to be the case.

Our RX 480 Hybrid mod, which utilized a liquid cooler rather than reference cooler, found that the RX 480 will draw upwards of 192W GPU power, as validated by software. The additional board components are rated for 40W pre-OC, so our overclocked card was likely drawing towards 250W. In such an instance, the GPU will overdraw power through the motherboard, which is potentially harmful to 24-pin headers (rated at 300-350W), the PCIe slot, and board power components. Our motherboard is capable of handling this extra power because we've taken measures to improve delivery, mainly by tapping into PSU power with an EVGA Boost cable and using an additional 6-pin board header for the PCIe bus.

On setups without these precautions, there may be an issue.

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