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AMD Radeon R9 390X and 390 reviewed: Hawaii rebooted

By Koh Wanzi - 21 Jul 2015

Introduction: A Familiar Architecture

AMD returns to Hawaii with the Radeon R9 390X and 390 graphics cards.

Same same but different

The top-end of AMD’s new 300-series of graphics cards just got a lot more interesting. AMD has broken precedent with its 200-series cards, and the Radeon R9 390X and 390 no longer comprise the best of what AMD has to offer in 2015. If you’re reading this review, you probably already know that the crowning jewel of AMD’s 2015 graphics card line-up is the newly-coined AMD Radeon R9 Fury X.

You’re probably wondering ‒ how could that make the R9 390X and 390 more interesting?

Let’s just say that by offering a new flagship under a new name and upgrading its existing line-up of cards, AMD has created a more diverse product portfolio. The Radeon R9 Fury X and Fury are without doubt the cards enthusiasts will look to when they want the very best from AMD, but these consumers comprise the minority of the overall graphics card market.

The majority of consumers instead seek to find a balance between performance and value, and the Radeon R9 390X and 390’s entrance into the upper-end of the mainstream graphics card market could be a boon to consumers looking for performance, but don’t necessarily want to absolute best.

This is helped along by the lower launch price of both cards. While the Radeon R9 290X and 290 were originally launched at US$549 and US$399 respectively, this year’s Radeon R9 390X and 390 come in at just US$429 and US$329 each.

Note that we also mentioned that AMD has upgraded, rather than replaced its 200-series of cards. That’s because like the Radeon R9 380 and R7 370 below it, the Radeon R9 390X and 390 are essentially rebadges of last year’s 200-series cards.

The Radeon R9 290X and 290 saw AMD debut its new Hawaii GPU architecture, which AMD has returned to on the R9 390X and 390. It’s slightly disappointing that AMD has nothing new to offer below the top-end Fury X, but we suppose the lower price somewhat makes up for it.

 

What’s in a name?

That which we call a rose, by any other name would smell as sweet. We see a return to Hawaii on the R9 390X and 390, but AMD has decided to rename the architecture to Grenada XT. But despite the spanking new name, the new cards are still very much Hawaii GPUs at heart.

The biggest changes when compared to the Radeon R9 290X and 290 come in the form of higher core and memory clocks (thanks to a mature GPU design, but it may impact the overclocking headroom) and an impressive 8GB of GDDR5 memory. Between the two cards, the differences can be narrowed down to the number of Compute Units (CU) enabled per Shader Engine and the core clock speeds.

Here’s a look at the block diagram for the Radeon R9 390X:

The Radeon R9 390X retains 44 CUs across four Shader Engines.

The Radeon R9 390X has 11 CUs enabled per Shader Engine, for a total of 44. On the other hand, the R9 390 retains the four Shader Engines but has just 40 CUs because one is disabled in each Shader Engine.

The number of stream processors also remains unchanged from the 290 series, with the R9 390X featuring 2816 stream processors and the R9 390 a more modest 2560.

You could say that AMD has taken the easy way out and simply ramped up clock speeds to improve performance over last year’s cards. In comparison to the reference clock of 1000MHz on the Radeon R9 290X, the Radeon R9 390X sports a 1050MHz core clock. Similarly, the Radeon R9 290’s reference clock of 947MHz has been bumped up to 1000MHz on the Radeon R9 390.

In addition, memory clock speeds have been increased from 5000MHz to 6000MHz, equivalent to a sizeable 20% boost over the previous generation. AMD made a conscious decision on the original Hawaii GPU to stick to wide and slow memory controllers in order to maintain better power consumption figures. However, it has abandoned this entirely now by ramping up the memory clock speeds by quite a significant amount, consequently increasing the available memory bandwidth on both cards to 384GB/s, compared to 320GB/s previously.

This is actually quite a lot of bandwidth to work with. To put things in perspective, the NVIDIA GeForce GTX Titan X – the undisputed single-GPU performance champion – has just 336.5GB/s of memory bandwidth. At 384GB/s, the Radeon R9 390 series of cards have the highest memory bandwidth available to any GDDR5 graphics card today.

And when you consider that increasing numbers of gamers are demanding to play at resolutions exceeding 1080p, this may just give the new Radeon cards a leg up in situations where the lack of memory bandwidth could potentially hurt performance.

The Radeon R9 390 series look poised to do well in situations where memory bandwidth is a limiting factor.

Furthermore, the onboard 8GB of GDDR5 memory makes the card look good beside competing NVIDIA cards, on paper at least. For instance, the only card to have more GDDR5 memory is the 12GB GeForce GTX Titan X. In comparison, the GeForce GTX 980 has 4GB of memory, and even the GeForce GTX 980 Ti has only 6GB.

According to PC World, AMD also said that the Radeon R9 390X and 390 are not merely juiced up versions of the R9 290 series cards, and in fact feature improvements to power management and efficiency. Incidentally, the 290 series cards have indeed received a lot of flak for their high power consumption (which can be as high as 400 watts), especially when compared against NVIDIA’s second-generation Maxwell cards.

However, both the Radeon R9 390X and 390 have a Thermal Design Power (TDP) of 275 watts, which is the same as that of the Fury X. And as we’ll see in our power consumption tests later, total power consumption hasn’t exactly gone down – in fact, it’s gone up. As a result, when AMD talked about better power efficiency, it might have been referring to less overt metrics like performance-per-watt.

In addition, AMD has reportedly told AnandTech that it is now using 4Gb GDDR5 chips in the 390 series cards, as opposed to 2Gb chips in the 290 series. These chips have better timings and operate at lower voltages than the 2Gb variants, which supposedly helps to reduce power and allow the 20% increase in memory clock speeds.

Nevertheless, we remain skeptical as to how much of a change ‒ or rather a change that end users will notice ‒ AMD can effectively bring about in the card’s power profile, seeing as both R9 390 cards are still based on the same Hawaii GPU architecture as their predecessors.

We’ll take a closer look at the design of the cards in the following sections. AMD hasn’t provided us with any reference samples, so we’re using the MSI Radeon R9 390X Gaming 8G and PowerColor PCS+ Radeon R9 390 to get an idea of what AMD’s new cards are capable of.

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