AMD Athlon X4 845 Review: A Perfect Budget CPU For Gaming And Multitasking

Introduction

A few months ago, AMD released a refresh of their popular Kaveri APUs and along with that, they released the Athlon X4 845 CPU. The Athlon X4 845 is the most interesting chip AMD has released thus far because this is the first desktop processor featuring the company's new 28nm Excavator architecture technology, an updated version of the Steamroller architecture featured on Kaveri processors which launched in June 2014.

AMD's Athlon X4 845 utilizes the FM2+ socket and it is based on the Carrizo die with the GPU and FCH (Fusion Controller Hub) disabled. The Excavator architecture technology is the company's final revision of the Bulldozer family and will accompany us until 2017. The next generation architectures that will replace the Excavator architecture will be the x86-64 Zen and AArch64 K12 architectures.

The Athlon X4 845 features four Excavator cores or two Excavator modules, clocked at 3.5GHz base and 3.8GHz maximum turbo boost. It has 2MB of L2 cache and no L3 cache since AMD's APUs have never had L3 cache and the Athlon CPUs are technically APUs but with the GPU cores disabled.

The Athlon X4 845 offers eight PCI-Express 3.0 lanes which is plenty if you are building a budget gaming machine and you will never really run into a GPU bottleneck unless you plan on doing Crossfire/SLI setup but in that case you'd probably better invest in a better CPU.

The biggest change with the Excavator architecture is not performance improvement but rather the focus on reduction in energy consumption which explains the TDP of 65W. AMD has managed to achieve a 23% area reduction with the Excavator architecture in the same 28nm technology node compared to Steamroller. Along with with other core optimizations such as prefetch improvements and lower latency, AMD has also managed to double the capacity of the L1 data cache without increasing power consumption and this should offer a 5-10% percent increase in IPC.

The Athlon X4 845 comes bundled with an improved heat sink and fan that is much better than the previous AMD's stock cooler. Stock heatsinks often are loud and most users usually swap them for an aftermarket cooler but the new cooler offers great cooling and acoustic performance.

AMD has sent me the ASRock A88M-G/3.1 motherboard which has a nice color scheme and I really like that the VRMs have heatsinks which you don't see often with most FM2+ motherboards. Overall, this is a pretty good FM2+ motherboard that has plenty of SATA ports, four RAM slots, USB 3.1 Type-C and high quality audio.

Some older FM2+ motherboards will not work with the new X4 845 processor so make sure you are using a compatible motherboard and remember that you need the latest BIOS to run the Athlon X4 845 CPU.

Comparison

AMD Athlon X4 FM2+ Processors Lineup
Model:	AMD Athlon X4 835	AMD Athlon X4 840	AMD Athlon X4 845	AMD Athlon X4 850	AMD Athlon X4 860K	AMD Athlon X4 870K	AMD Athlon X4 880K
CPU Process Node:	28nm	28nm	28nm	28nm	28nm	28nm	28nm
CPU Codename:	Carrizo	Kaveri	Carrizo	Godavari	Kaveri	Godavari	Kaveri
CPU Architecture:	Excavator	Steamroller	Excavator	Steamroller	Steamroller	Steamroller	Steamroller
Cores / Threads:	4/4	4/4	4/4	4/4	4/4	4/4	4/4
Core Clock:	3.1 GHz	3.1 GHz	3.5 GHz	3.2 GHz	3.7 GHz	3.9 GHz	4.0 GHz
Boost Clock:	N/A	3.8 GHz	3.8 Ghz	3.9 GHz	4.0 GHz	4.1 GHz	4.2 GHz
L2 Cache:	2MB	4MB	2MB	4MB	4MB	4MB	4MB
L3 Cache:	N/A	N/A	N/A	N/A	N/A	N/A	N/A
TDP:	65W	65W	65W	65W	95W	95W	95W
Socket Support:	FM2+	FM2+	FM2+	FM2+	FM2+	FM2+	FM2+

The Athlon X4 845 is not the only processor featuring the Excavator technology, AMD also plans on releasing the X4 835 processor. Not much is known about the X4 835 but it looks like it has the same specifications as the X4 845 but it runs at a lower frequency. Since these CPUs are not K versions, the multiplier is locked on both.

AMD's Excavator Architecture Features

The engineers at AMD have been busy tweaking and improving the Excavator architecture and the biggest change that they have made to the architecture is doubling the size of each core's L1 data cache to 32KB from 16KB while keeping the same latencies. They have also cut down the size of the L2 cache to save die space from 2MB on Steamroller to 1MB per module. AMD has reduced the power consumption of the L1 data caches through better clock gating and other array changes by up to 50%.

Another big improvement to architecture is the increase in target buffer size in branch prediction which has been increased from 512 to 768 entries. AMD has also added support for some new instructions, including the AVX2 suite and MOVBE, SMEP, and BMI1/2.

AMD has switched from using a High Performance Library (HPL) in Steamroller to a High Density Library (HDL) design in Excavator. The usage of high density library design has allowed AMD to make the Excavator cores 23% smaller compared to Steamroller cores inside Kaveri which in the end has reduced the power consumption by 40%.

Each Excavator core incorporates 10 Adaptive Operation (AVFS) modules containing 500 frequencies sensing paths, this improves energy efficiency across the entire voltage/temperature range. AMD has also increased the transistor count to 3.1 billion in Carrizo from 2.41 billion count in Kaveri.

The function of Adaptive Operation (AVFS) modules is to help utilize each core to the fullest by balancing between the voltage, temperatures and available headroom. This provides an additional power reduction level over the High-density library gains.

Packaging & Accessories

The Athlon X4 845 comes packaged in a simple but effective elegant box that is mostly black/dark gray. Since the Athlon X4 845 doesn't have an integrated GPU, you will see a reminder on the bottom left that this CPU requires a discrete GPU.

Moving on, there's a white section on top of the box that labels what you'll find inside. It lists the 3.5Ghz base and 3.8Ghz turbo frequency, 2MB of cache, socket FM2+ and heatsink and fan.

The heatsink comes wrapped around a cardboard that securely holds it in place.

The ASRock A88M-G/3.1 motherboard has plenty of space around the CPU region if you decide to install an aftermarket cooler with a big fan.

The New Stock Cooler

This is the new 95W thermal solution cooler that comes bundled with the X4 845. It's simply being called the Near-Silent 95W Thermal Solution and as its name suggests, it can handle a 95W TDP profile. I took out the Wraith cooler to compare it against this new cooler. The 95W thermal cooler weighs approximately 380 grams while the Wraith comes in at 455 grams.

Here's the Wraith cooler side by side with the Near-Silent 95W Thermal cooler. The dimensions for the Wraith are 8cm tall, 18cm wide and 11cm deep while its little brother is about 4cm tall, 8cm wide and 8cm deep. Both coolers ship with pre-applied thermal paste to make the installation quick and easy.

When it comes to fin count and fin thickness, the Wraith has 50 aluminum fins each being 0.33mm thick and the 95W thermal cooler has 30 fins each being 0.42mm thick. The Wraith has four heatpipes made out of copper and each heatpipe is about 6mm thick. The 95W thermal cooler on the other hand is made out of only aluminum fins and doesn't have any heatpipes.

Test Setup & Power Consumption

Test Setup
Processor:	AMD Athlon X4 845 Intel Pentium G4400
Motherboard:	ASRock A88M-G/3.1 MSI H110M Pro-VD
RAM:	Kingston HyperX 8GB DDR3 2133Mhz G.SKILL Ripjaws 8GB DDR4 2133Mhz
Graphics Card:	Sapphire R9 390X
Storage:	Samsung 840 Pro 256GB
Power Supply:	Antec HCP 850W
Case:	Corsair 750D
OS:	Windows 8.1 64Bit
Thermal Compound:	Noctua NT-H1
Heatsinks:	AMD Stock Cooler Intel Stock Cooler

I have prepared a number of different test setups for the Athlon X4 845 processor. I'm comparing the X4 845 against the Pentium G4400 because it also retails for around $70 and it is a popular CPU among users who are on a tight budget for a gaming computer. The integrated GPU on the Pentium G4400 will be disabled and I will be using the Sapphire R9 390X to make the testing as accurate as possible. Keep in mind that the Pentium G4400 doesn't officially support DDR3 and Intel doesn't recommend using it so I will be using DDR4.

Idle power consumption of the entire computer will be measured after leaving the computer idle for 20 minutes. Load power consumption of the entire computer will be measured after playing Witcher 3 on max settings at 1080P for 20 minutes. I want to make it clear that power consumption measurements will differ per computer and components from my measurements if you add optical drives, HDDs etc.

All of the testing is done with an ambient temperature of ~19C. CPU-Z will be used to verify the CPU speed and the voltage being used in Windows 8.1. Also, the CPUs are tested with the default settings (Turbo, C1E etc) enabled in the BIOS.

Despite the fact that the Pentium G4400 is built on 14nm manufacturing process, the Athlon X4 845 does very well in both idle and load. The R9 390X alone consumes roughly 15 watts in idle so if you subtract that from the idle power consumption, you will get how much the entire computer consumes without the GPU. So far I am very impressed by how efficient the Excavator architecture is.

CPU Performance Results

Looking at the Cinebench chart above, we can see that the X4 845 offers amazing multi-core performance and the single-core performance isn't too bad either compared to the Pentium G4400.


Obviously the X4 845 wins this test due to having four cores.


Geekbench 3 shows a similar result as Cinebench. The X4 845 loses in single core performance but makes up for it in multi-core performance. AMD has always struggled with single core performance but hopefully Zen will take care of that.


Moving on, the X4 845 once again delivers very good multicore performance.

AMD Athlon X4 845 In Gaming

Here we can see the Pentium G4400 offering better fps despite having only two cores.


Both CPUs performed relatively the same in Metro Last Light.


Similar performance from both CPUs in Battlefield 4.

Value & Conclusion

I'm very confident to say that the Athlon X4 845 is without a doubt the best chip AMD has created in the last couple of years. As a tech enthusiast, I'm very happy to see AMD deliver a great processor that combats the competitor's in the budget segment. The Excavator architecture is a true upgrade to Steamroller architecture. The Athlon X4 845 would have been even better if it was unlocked and could have been a true challenge to Intel in even against the Core i3/i5.

Pros:
+ Superb Multi-Core Performance
+ Low Power Consumption (65W TDP)
+ Supports Fast 2133Mhz DDR3 RAM
+ Supports New x86 Instructions
+ Double L1 Data Cache
+ Quiet Stock Cooler

Cons:
- Not Unlocked

Overall, I am very impressed with how well the X4 845 performed against the Pentium G4400. The X4 845 is a perfect low-cost processor for gaming and multi-tasking. It's very hard to beat with its great multi-core performance and price.

AMD did a fantastic job with the Excavator architecture and it shows with the X4 845. I would recommend the X4 845 processor to anybody who wants to build a nice budget gaming machine. The Athlon X4 845 is the best bang for your buck processor out there until Zen arrives.

Final Score    9.0