AMD A8-3870K APU Review

While APU’s (accelerated processing units) may not be as exciting as the top of the line speedsters put out by Intel, they do have their place in advancing processor technology. With the release of the first unlocked APU, the A8 3870K, AMD steps closer to making the APU a viable option for your every day computing and gaming needs.

Features and Specifications

APU’s are aimed to be low power-consumption CPU’s with better than integrated video GPU’s. They’re also supposed to be light on the wallet. So, they are meant for multimedia decoding and light 3D acceleration; think HTPC, media server, or basic desktop system.

Overclocking

The stock reference clock on the A series “Lynx” platform is 100 mHz. This reference clock sets the base frequency for the CPU, GPU, memory, North Bridge, SATA, and USB. Because all these subsystems are effected, overclocking via reference clock can sometimes be very tricky. Black Edition or unlocked processors allow you to change the multipliers while leaving the reference clock alone, putting less strain on the overall system, and thus are more desirable for overclockers like us.

AMD sent over a fairly in-depth overclocking guide with the A8 3870K that was filled with nifty tips and tricks to push this processor to it’s fullest. The main things in that guide that were slightly different than overclocking a normal processor were:

• Use an HDMI or DVI monitor when overclocking the GPU
• Leave the CPU at stock, or possibly underclock the CPU, to get the most out of the GPU. The reverse is also true if you want more CPU performance. This makes sense because the CPU and GPU are on the same chip and creating heat together. Decreasing one leaves more room for the other.
• “NCLK (north bridge clock) has a notable effect on overall system performance.” I didn’t specifically test this statement, but you will see it roughly increase 1:1 with memory clocks.
• To get higher reference clocks, change the SATA mode to IDE. AHCI mode is stated to limit the clock speed to about 5% over stock, or roughly cap at 105 MHz. IDE mode should allow for 33% increase, or a running clock of 133 MHz.

In the same document, AMD also stated some targets for overclocking. So, I had a pretty good idea what I was aiming for when I finally got the chip installed and turned on.

GPU clock => 800 – 960MHz (@ 1.20….1.30V)
NB clock => 900-1100MHz (@ 1.20…1.30V)
CPU clock => 3500-3800MHz
Memory clock => 933-1200MHz (depending on DIMM spec)
ref. clock => up to 105MHz (in AHCI mode) / up to 150MHz (in IDE mode)

In my own testing, I found the values listed above to be very accurate. The highest CPU clock I was able to achieve was 3850 MHz (35×110 MHz, 28% increase) but I had to drop down to 3720 MHz (31×120 MHz, 24% increase) to complete benchmarks while on air cooling.  For the GPU, I could only hit 864 MHz (44% increase).  My maximum base clock was 160 MHz and I was able to push my RAM to 1080 MHz (800 MHz stock, 35% increase).

Benchmarks

For the different tests, I compared the A8 3870K against other systems I have tested in the past. Unfortunately, the number of tests we run has changed over time and I didn’t have time to go back and rerun them on the older hardware, so some of the systems are missing some of the tests (represented as 0.00 in the graphs below).

Hardware Line Up

Tests

The main thing to take away from these compute tests is that the A8-3870K running at stock 3.0 GHz actually performs like a normal dual core Phenom II processor, even beating the 3.3 GHz 560 BE in a few tests. This might not be amazing to some of you, but for others, like me, this is very nice to see.  Personally, I was expecting performance to be more on-line with the E series processors (like the E-350 in the Zotac Fusion A board). Of course, the different RAM speeds might have played a small part in the A8-3870K doing better, but I think it’s safe to assume that wouldn’t have caused the large marins in the 2nd graph.

For the gaming and graphics tests, I added the Biostar Nvidia Geforce GT240 and AMD Radeon HD 5550 to the mix. These are two other low power HTPC cards I tested in the past. Unfortunately, like the graphs above, I didn’t have data from all of our current tests. But, I still wanted to show how they compared in the tests I did have data for. So, I apologize in advance if the graphs are little ugly with all the missing data, but hopefully they are still informative.

What I like about these graphs is that they show the new A8-3870K blows away any other current integrated graphics offering. This doesn’t mean that you can play the newest games at full settings and full resolution, but it does mean that newer GUIs that are 3D accelerated will be smoother and video rendering will be better. So, these A8 processors will work well as a cheap desktop, workstation, or HTPC but you should still add in a discrete GPU if you want to play games.

Conclusion

Overall, the AMD A8-3870K APU did very well and exceeded my expectations. It performed very well when compared against other integrated graphics solutions and even when compared against other low-cost processors. Most importantly; it overclocks fairly easily! So, us hobbyists who like to stretch our wallet and tweak our hardware will have a great time with this chip. Sure, it’s no hotrod, but for the price ($119.99 at Newegg right now) you get decent computation capabilities and graphics capabilities in one little package. Mainly for the better-than-average 3D performance, I’m marking this processor Overclockers Approved.

Thanks, AMD, for sending this processor over for testing.

– splat