AMD Athlon X4 845 Review: Excavator digs AMD out from under Intel

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  • Pros

    • Solid multi-core performance
    • Very quiet stock cooler
    • Terrific value at current street prices
    • Low power consumption
  • Cons

    • Slow single-thread performance
    • No integrated GPU
    • Not unlocked
    • Supports 2133MHz DDR3 but not DDR4

AMD Athlon X4 845

AMD Athlon X4 845

There was a time (back in the days of overheating Pentium 4 processors) when the PC industry believed that AMD and its family of high-performance, high-value processors would replace Intel as principal manufacturer of CPUs. More than a decade later AMD has been largely eclipsed by the market successes of Intel and several generations of its Core-series processors. But while Intel has focused on pushing for faster clock speeds and delivering lower power consumption by moving to a 14nm architecture, AMD has quietly been optimizing its 28nm architecture to deliver similar power efficiency and greater performance per watt in the entry-level and “mainstream” PC market.

This is where AMD’s Athlon x4 845 and the new “Excavator” architecture made the equivalent of a stealth bomber attack against Intel earlier this year. The new Excavator cores won’t compete with the newest high-end Intel Core i7 chips, but AMD might have just found a way to bury Intel’s budget-priced Pentium line.

A closer look at the Athlon X4 845

DSC03774Unlike the other CPUs (technically APUs) in the early 2016 line of AMD FM2+ desktop processors which are based around the older “Steamroller” cores combined with discrete GPU cores, the Athlon X4 845 features four separate 28nm Excavator processing cores (grouped in two nodes) and no graphics cores. The main features of the Excavator core are larger L1 data cache with lower latency and improved prefetch as well as better branch prediction with a 50% increase in the Branch Target Buffer size.

That technobabbel in the previous paragraph means Excavator delivers slightly more efficient (faster) processing than AMD’s Steamroller cores in the previous Kaveri platform. Unfortunately, the larger L1 cache and better prefetch in the Excavator cores is at least partially offset by the fact that Excavator runs on half as much L2 cache as the previous generation of AMD processors.  As a result the biggest practical improvement that the Excavator architecture brings to the table is better performance per watt rather than better overall performance. Each node (two of the four cores) in an Excavator-based CPU is 23 percent smaller than the same 28nm node in a Steamroller-based CPU. This explains how the new X4 845 has a TDP of just 65W yet still performs marginally better than a 95W CPU from the previous generation.

The team at Notebook Review wanted to take a closer look at this desktop processor because it gives us an unobstructed view of the processing power of AMD’s Carrizo platform and the Excavator cores found in the newest AMD-based notebooks for 2016.

DSC03773DSC03780

AMD provided us with a review sample of the Athlon X4 845 along with the ASRock A88M-G/3.1 Micro ATX motherboard for our tests. The street price of the processor (with the included cooler) and the motherboard comes to just under $130 at the time of this writing; meaning this CPU and motherboard combination are aimed squarely at system builders who want an affordable PC with enough room for high-performance upgrades like support for PCI Express 3.0 x16 graphics cards and M.2 PCIe Gen2 x4 SSDs.

If there is a potential shortcoming to this desktop package it’s the lack of support for DDR4 system RAM.

DSC03777AMD Athlon X4 845 Specifications:

  • Cores/Threads: 4/4
  • CPU Platform: Carrizo
  • CPU Architecture: 28nm Excavator
  • Core Clock: 3.5 GHz
  • Boost Clock: 3.8 GHz
  • L2 Cache: 2 MB
  • CPU Socket: FM2+
  • DRAM Frequency: 2133
  • TDP: 65W
  • Heat Sink: 95W Cool ‘n’ Quiet Thermal Solution
  • MSRP: $60

Test Setup:

  • AMD includes a 95W Cool 'n' Quiet Thermal Solution inside the box with the Athlon X4 845

    AMD includes a 95W Cool ‘n’ Quiet Thermal Solution inside the box with the Athlon X4 845

    CPU: AMD Athlon X4 845
  • Motherboard: ASRock A88M-G/3.1
  • RAM: 2x 4GB G.SKILL Ripjaws X Series DDR3 2400 (PC3 19200)
  • GPU: Nvidia GeForce GTX 980
  • Storage: Kingston HyperX Savage 480GB SSD (SHSS37A/480G)
  • PSU: Antec TruePower Classic series TP-750C 750W
  • Heatsink: AMD stock cooler
  • Thermal Compound: Arctic Silver 5
  • OS: Windows 7 Professional 64-bit

Performance

The Athlon X4 845 is noticeably quicker launching and switching between apps and performing computational tasks than the previous generation (Kaveri) AMD Athlon X4 860K or the AMD A10-7850K. That said, the real-world difference in speed would largely go unnoticed by most consumers unless they did a side-by-side comparison between all three processors.

Comparing the X4 845 to Intel’s current Skylake-based Pentium G4400 produces mixed results. The dual-core Intel CPU delivers better single-core performance in basic processing tasks that only require one core but the quad-core Athlon consistently completes tasks that require multi-core processing in close to half the time.

The one performance area where we did observe a clear improvement in overall speed compared to both previous-generation AMD processors and current generation Intel Pentium CPUs was when editing and rendering 1080p and 4K video files; the X4 845 was obviously faster.

Benchmarks

Wprime 32M results in seconds (lower is better):
x4845wprimechart

Cinebench R15 Single Core Score (higher is better):
x4845CineSinglechart

Cinebench R15 Multi Core Score (higher is better):
x4845CineMultichart

Geekbench 3 Single Core Score (higher is better):
x4845GeekSinglechart

Geekbench 3 Multi Core Score (higher is better):
x4845GeekMultichart

PCMark 8 Home Score (higher is better):
x4845PCM8homechart

PCMark 8 Work Score (higher is better):
x4845PCM8workchart

Power Consumption

While most desktop PC builders aren’t too concerned about the power consumption of their CPU there are others who believe that every watt matters. To that end, AMD didn’t just focus on minimizing the power consumption of the Excavator architecture while the cores are idle and under load. AMD engineers also made sure each core drops into idle mode as soon as it isn’t needed … and each core pops back into full voltage for intense processing quicker than previous generation CPUs.

As a result, the 65W Athlon X4 845 and its four 28nm Excavator cores consumes slightly less power in one hour than a similarly configured desktop with Intel’s dual-core 65W Pentium G4400 based on 14nm Skylake architecture. Our test configuration of the AMD Athlon X4 845 consumed just over 57W during idle while the desktop running the Intel Pentium G4400 consumed 62W at idle. When we pushed both CPUs to full load running Call of Duty: Black Ops III and the desktop with the X4 845 consumed 285W under load while the Pentium G4400 topped out at just under 268W.

In short, Intel 14nm process still has a slight advantage in total power consumption if you are constantly pushing your CPU to its limits, but AMD has clearly optimized the 28nm Excavator architecture to deliver similar (or lower) total power consumption during normal use as the CPU switches between idle and full power.  This type of power management is even more important for notebooks running AMD Carrizo APUs based on the Excavator architecture this year.

Conclusion

At the end of the day the AMD X4 845 wasn’t designed for people who spare no expense for the fastest technology that money can buy. Rather, the X4 845 is a budget quad-core CPU for desktop builders who expect even a value-priced desktop to “keep pace” with modern technology. We can’t say that AMD is back in a dominant position against Intel overall, but the Athlon X4 845 is better than Intel’s current line of budget-priced Pentium CPUs and rivals previous generation Core i3 and Core i5 chips. Competition is a good thing for consumers and the Excavator architecture delivers several improvements over the older Steamroller architecture.

If you want to build a low-cost gaming rig and need a processor that costs less than $70 the quad-core Athlon X4 845 is far more appealing than the dual-core Intel Pentium G4440 or the older Pentium G3258. In short, AMD’s new Excavator architecture arguably delivers “the best bang for your buck” at entry level prices.

AMD Athlon X4 845

Pros:

  • Solid multi-core performance
  • Very quiet stock cooler
  • Terrific value at current street prices
  • Low power consumption

Cons:

  • Slow single-thread performance
  • No integrated GPU
  • Not unlocked
  • Supports 2133MHz DDR3 but not DDR4


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  1. simpsane

    Independant benchmarks score the G3258 higher than this, and then of course the G4400. In conclusion, AMD has created another inferior product.