CPU Performance: Athlon 860K or A10-7850K

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Kammex

Kammex

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I'm thinking of making a FM2+ build, and since I am going to use a decent GPU (R9 280 or 285), I'm going to need the best CPU. I know that the 7850K is an APU, that it would be better if I take advantage of the iGPU, but I just need the best CPU performance, so which one would be better? Thanks in advance. :)
 
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Shehriazad
I have both the 860K and the 7850K and I have found a DECISIVE difference between the 2.

Voltage. The Voltage differs TONS.

If I use the automatic voltage control or use the auto boost as permanently enabled clock then the voltages look the following:


3.7 GHZ
A10 7850K: CPU 1.332, CPU NB 1.115
860K: CPU 1.325, CPU NB 1.075

Permaboosted to 4 GHZ
A10 7850K CPU 1.4200, CPU NB 1.200
860K CPU 1.4000, CPU NB 1.075.

Of course manual OC values look different, but the 860K always runs stable at far lower voltages for me (even with disabled iGPU on the 7850K)


The CPU NB of the 7850K will get volted up (and actually needs more for stability after some manual testing) even if the iGPU is DISABLED. Overall the 860K will run...
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slyu9213

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Performance wise they should be near identical as the 860K is the 7850K without the IGP enabled(for any reason).
But as you will be using a discrete video card in the FM2+ build there is no reason to get the more expensive 7850K over the 860K.

Both 7850K and 860K should overclock to around 4.5-4.6GHz. 4.7GHz seem to be the highest stable speeds I have seen so far but some CPU/APUs may need additionally higher voltages.

The only point where the 7850K gets a performance advantage over the 860K is when/if AMD allows the IGP to be used as extra computing/graphics power in games/software like dedicated physics calculation (TressFX). I have a feeling that this could happen in the future but AMD has been really quiet so I no one really has any ideas. Also if AMD allows the IGP to be used as physics calculation, then who's to say we can't use another discrete card as the extra power.

For Maximum performance on the FM2+ socket the 860K is the winner. The 760K can trade hits with the 860K due to it's higher overclock headroom (~5GHz) but even then Kaveri has a 10-20% IPC improvement over Richland so a 4.5GHz 860K should be equal with a 5GHz Richland.
 
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Shehriazad

Shehriazad

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Feb 20, 2014
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I have both the 860K and the 7850K and I have found a DECISIVE difference between the 2.

Voltage. The Voltage differs TONS.

If I use the automatic voltage control or use the auto boost as permanently enabled clock then the voltages look the following:


3.7 GHZ
A10 7850K: CPU 1.332, CPU NB 1.115
860K: CPU 1.325, CPU NB 1.075

Permaboosted to 4 GHZ
A10 7850K CPU 1.4200, CPU NB 1.200
860K CPU 1.4000, CPU NB 1.075.

Of course manual OC values look different, but the 860K always runs stable at far lower voltages for me (even with disabled iGPU on the 7850K)


The CPU NB of the 7850K will get volted up (and actually needs more for stability after some manual testing) even if the iGPU is DISABLED. Overall the 860K will run cooler and have more headroom for air overclocks due to the lower voltages. Especially the big difference in CPU NB makes a difference.

All in all my 860K runs 5° colder on the same clocks...and I was able to push it 400 MHZ further with the same air cooling system than my 7850K.(I managed 4.4 GHZ with 7850K and 4.8GHZ with my 860K with a lousy Scythe Katana cooler)

So unless you REALLY want the iGPU (which is only good if you invest in expensive ram, trust me on this one) I would DEFINITELY favor the 860K.

Im not sure where you are from...but in my country the 860K right now only costs 65€....that's a steal. I'm not sure why most sites either don't test the 860K or don't realize the voltage difference...and thus higher OCing potential.

TL;DR - If you want a CPU that runs colder, eats less power and has more OC headroom take the 860K. If you really want the iGPU for whatever reason then take the 7850K
 
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slyu9213

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Wow 4.8GHz? What kind of voltage settings did you need? I have a 860K coming this Friday-Saturday and it would be interesting to know.

For the OP

860K, GTX 770, 8GB 1600MHz

Far Cry 3 @ 1080p
Stock: 30FPS
4.5GHz: 31FPS

Metro 2033 @ 1080p
Stock: 58FPS
4.5GHz: 53FPS

Watch Dogs @ 1080p
Stock: 39FPS
4.5GHz: 35FPS

Sleeping Dogs @ 1080p
Stock: 108FPS
4.5GHz: 111FPS

What I find interesting, from Overclock3D's review, is that the 860K gets a performance boost from using 1866 to 2400 in gaming. The boost is about the same as when you go from stock to 4.5GHz.
 
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Shehriazad

Shehriazad

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Interestingly enough I get to 4.8 GHZ @ 1.42 CPU VID...but I don't need to touch the NB VID AT ALL(raising it did not allow me to get to 4.9). It stays at 1.0750

With the 7850K I needed 1.43ish VID and 1.2 NB VID which means a bunch of extra temperature comes from the 1.2 NB VID.

I think the real temp trouble maker in the 7850K chip is actually the NB....not to mention that throttling occurs if you have the iGPU enabled (and the base power draw is also higher, putting further strain on your components)

I could probably go above 4.8...but only if I got better cooling and OC'd the FSB....which I absolutely do not want to do.

Temperature wise the 860K get's close to 59° in stress tests but hasn't gone above 50° in benchmarks and games. (keep in mind that my CPU sits in an ITX case, bad airflow)

My 7850K starts throttling in benchmarks and goes to 65° during stress test at a mere 4.4 GHZ.

Mind you that all those values are in the exact same setup with just the CPU switched.


I would say that AMDs APU technology is still suffering from a few "infant diseases". I hope that Carrizo makes up for this.


Edit: Also I can confirm that faster ram affects even the CPU performance a lot. I guess it has to do with the lack of an L3 cache on those CPUs. I have both 1600 MHZ ram kits and a 2400 MHZ ram kit. The fps goes up quite a bit when using the 2400 MHZ kit...even though Im using dedicated graphics.
If the 860K came with an actual L3 cache instead of the GPU...we would have one hell of a legit CPU.

Darned hybrid products ;P
 
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slyu9213

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I know right? Thanks for the reply. I only have 1600MHz RAM so I'm going to have to buy some 2400MHz RAM next then. The voltage numbers look good too. I havn't overclocked an APU yet so I don't know if I want to overclock the FSB/BCLK when I get the 860K. I guess I'll have to try overclocking with just the multipliers and then with FSB/BCLK.

 
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Shehriazad

Shehriazad

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A word of advice...make sure that at least the board you are using supports 2400 MHZ out of the box. Even with boards that support it you will often enough run into trouble since the CPU "only" supports 2133 MHZ by itself.

I mean the worst that can happen is that the system doesn't boot up with 2400 MHZ...if you can help it buy a ram with AMP profile instead of XMP profiles...those work more often than not with AMD CPUs (for obvious reasons)
 
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slyu9213

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The motherboard I have is an Gigabyte F2A88XM-D3H. It supposedly supports 2400MHz RAM and AMP. I'll probably buy AMD's R9 2400MHz RAM, or something else if price differences is a lot. I could buy 2133 modules that are known to OC to 2400MHz.
 
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