AMD's Kaveri 7850k APU Extensive Review

[Guest]

Hello.

 

I'm an owner of the 7850k APU. Having used this hardware for almost a year now, I wish to share my insights on this product with you, especially stuff that is generally not reviewed or analyzed enough by others.

 

So, here are the contents of this review:

 

1. General description of the 7850k, target market and purpose.
2. Possible applications and recommended configurations.
3. Does overclocking make sense?
4. My rig, RAM and IMC performance.
5. Pros and Cons. What makes sense to buy.
6. Conclusion. Thoughts about future APUs and possible benefits.

 

1) General description of the 7850k, target market and purpose

 

The 7850k is what I consider a solid release by AMD in years. Although, this might sound controvertial to some since the CPU side of this APU is relatively weak, AMD still managed to pack what is nearly an SOC, on a single die with a 28nm manufacturing process. This indicates that the general layout or architecture of the chip is probably more advanced than the CPU cores themselves. In fact, you get many features and functionality with this chip (although not everything is that useful **cough cough*** true audio ***cough).

 

So where is this chip marketed towards? AMD markets the chip mostly towards online gamers as a cheaper alternative to CPU+dGPU combo. In that usage scenario, a well rigged solution based on the A10 can do a magnificent job with an overall good efficiency and low cost. So the purpose of making this chip was to basically try to obtain a beter foothold in the entry level segment but mostly on what you could call the competitive online segment of the market.

 

 

2) Possible applications and recommended configurations

 

In my opinion, this APU is good for the following applications:

 

• HTPC and entertainment platform capable of running 3D applications.
• Kind of SteamBox.
• Small form factor PC, especially in slim desktop cases.
• Entry level gaming PC with the option to achieve mid-range capabilities.
• All-around cheap workhorse (games, media, office work, light CAD etc.).
• Professional light workstation (especially the B variant for everyday office work and light GFXs apps).

In general, if you are opting for this kind of processor, you are not into spending too much money. Considering this, you will want to spend more money where it matters the most and not just shovel the money away for cool LEDs.

 

Case: I would recommend micro towers and slim desktop cases. If you don't care too much about your PC being ultra-small or want to preserve the option to upgrade, the micro tower offers better expandability, cooling and general options. If you need the PC for your living room or want the smallest possible PC with this APU, you will be better off with a slim case.

 

MoBo: FM2+ boards are either mini ITX or micro ATX. Both slim and micro cases usually accomodate both sizes. However, for the slim case, I would recommend either a mini ITX board or a smaller micro ATX with only two DIMM slots and lower height.

 

PSU: What power supply you need depends on how you are going to use the system. If you are going for a slim desktop,you should go for a maximum power of 350 Watts, while for other usages with a dGPU, you should go for something in between 350 and 500 Watts. For smaller cases, you will want to have a PSU with high efficiency in order to avoid thermal issues due to the PSU becoming hot and noisy.

 

Case Cooling: If you want very silent operation, Noctua's fans offer great performance but at a high cost. Can't recommend them for a cheap system. However, for slim cases which only have one 80mm fan position, buying only one noctua or any other high quality fan, kinda makes sense. You will mainly require very silent operation for living room usages, and higher cooling performance for gaming.

 

CPU Cooling: Aftermarket cooling is a must! I got greater stability and performance by installing an aftermarket cooler. This is due to the thermal margins of the processor. If you manage to keep it cool, it will throttle less, thus preserving its performance. Otherwise, your APU will throttle down more often. More on this later.

 

Storage: Oh dear, once you go SSD you never go back. My opinion here is terribly biased towards SSDs. I do not even consider HDDs anymore. For slim desktops, SSDs make up for a very lucrative solution mainly due to their absolutely silent operation and extremely low thermals. Use HDDs on micro cases if you need the extra, cheap storage.

 

 

3) Does overclocking make sense?

 

It depends.

Let us make an assumption regarding the usage and life cycle of a system. Let's say that you are short on cash and need a gaming rig fast for some online gaming. So you get your components, build your system and are ready to go. Now what? Should you overclock?

 

YES (and also no).

 

Download AMD's overdrive and squeezzzzzzz a few more MHz out of your iGPU. And you could say now: Why not OC the CPU as well?

 

Firstly, the APU throttles down when it detects load on the iGPU so you are gonna max out at 3.0 GHz anyway.

Secondly, the CPU performance at 3.0 GHz is more than enough for what the iGPU can offer.

Lastly, even by modifying the p states in order to get 4.0 GHz or more at the "throttled" state, your APU power consumption is going to rise from what is about 105 Watts to about 120 W or more. You will need very good cooling for that which is a no go for small PCs.

 

However, apart from overcloking the GPU side, there are two other things that will benefit your system a lot if overclocked. The RAM and the Integrated Memory Controller or IMC. More on that on section 4.

 

Now after a year of gaming on the iGPU, you want AND can upgrade to a dGPU. So you buy your graphics card, install it and realize that the iGPU is not of much benefit anymore but, on the other hand, you could use some extra juice from the CPU to cope with your newly acquired GPU.

 

This is the moment to OC the CPU side. If you disable the iGPU, you dedicate all of your RAM to your CPU as well as all of your available power and cooling capacity. Your CPU is not gonna throttle anymore and you will enjoy decent performance with any graphics card with performance up to what an R9 280/380 can offer. After that, your CPU is definitely gonna become a complete bottleneck unless you run Vulkan/Mantle or DX12.

 

 

4) My rig and experiences, RAM and IMC Performance

 

My rig:

Case: Collermaster Elite 342 micro tower.

APU: A10 7850k

RAM: Team Group Vulcan 2x4GB @ 2400MHz CL11, single rank DIMMs (FORMER) G.Skill Trident X  2x4Gb @ 2400MHz CL10, dual rank DIMMs (CURRENT)

MoBo: ASUS A88XM-E

PSU: Passive PFC 400W Evolveo PSU (good enough for low loads, made in europe)

Cooling: 2 extra 92mm fans for side inlet and rear exhaust. Some Artic Cooling fans. +1x 120m Coolermaster fan for frontal inlet (included with case).

APU Cooling: Noctua NH-L9a upgraded with 92mm Noctua NF-A9

Case Cooling: 1x frontal 120mm Noctua NF-S12Am, side 92mm Noctua NF-A9, rear exhaust 92mm Noctua NF-A9x14 (from heatsink)

Optical Drive: Samsung DVD RW

Storage: Samsung 840 EVO SSD 120Gb

 

G.Skill RAM was bought with an eye on building another PC for my brother with the Team Group RAM. So I combined an upgrade for me with another future build.

Also yes, I like Noctua's stuff.

 

OC:

IMC +100MHz, iGPU @ 900 MHz, extreme profile for G.Skill RAM with further tweaked secondary timings.

 

This review is not meant to provide you with exact numbers regarding FPS but mostly info on what you can and cannot do with this APU. Sooo, here are my experiences:

 

1) Skyrim on basically Ultra Settings, except resolution (1440x900), no MSAA (FXAA is enough for this res), and shadows on high. 30 to 60 FPS usually around 45 fps.

2) Thief, Mantle. 1440x900 medium settings, benchmark gave 25.0 fps minimum (avg over 30). Actual gameplay was usually well above 30 fps.

3) Source games, 1440x900 Ultra Settings more than 45 fps.

4) Sins of a Solar Empire, 1440x900, Single Player, lower RAM timings give great benefit here. Frames cap at 60. At normal speed, you can have some deeps of 20 fps in late game with large fleets and some AI opponents. Keep in mind that the code of this game is dated 32-bit with some issues regarding max memory use and stuff.

5) Bitcher 2... I meant Witcher, Witcher 2 of course, 30-50 fps but 1280x800 with low+ settings, normal viewing distances, bloom, no texture downscaling and normal memory footprint.

6) Mount and blade Warband: hehe no problem there.

7) Planetside 2: This one is interesting: 1440x900 with render quality of 89%, textures on high, graphics quality on medium, models on medium, bloom off and other stuff on low. FPS can exceed 65 BUT, in large battles (biolabs), you kinda get 25 fps. However, with the single rank, higher timings of Team Vulcan RAM, I used to go below 20 in those situations. Better latency proves to improve those cpu intensive situations by quite a bit.

8) Media playback: no issues, audio quality set at Studio level quality 24bits 48000Hz.

9) Office work is fluent,  light CAD apps are no problem, boots in less than 12 seconds in Win 7 64-bit.

 

Now, let's talk about RAM and the IMC of the Kaveri APUs. Let's take a look at the results from AIDA 64 with the G.Skill RAM:

 

There are two numbers that stand out in the CPU Memory Benchmark, the write performance and the latency. If you check the second image with the results of the GPGPU benchmark you will see that the write speed is prety much the same. Why? I think it is due to the architecture of the IMC, although I'm not an expert in these matters, it seems that the IMC cannot handle many write instructions (?) per cycle. A Pentium with decent 1600 MHz RAM generally has higher performance than the A-10 in regards to write speed. This in my opinion is the bottleneck of the iGPU, IMC write performance.

 

In regards to high latency, it seems to be a matter of low clock for the IMC. The result you see in the image above is with a slight OC of 100 MHz on the IMC. Another 100 MHz with significantly higher voltages brings the latency down by about 2ns. Team Vulcan RAM with IMC at 1900MHz and lots of timing tweaks, yielded a latency of about 77.5ns. Better latency should mostly benefit the CPU since on common workloads, the CPU doesn't fully utilize the bandwidth of the RAM but still requires quick response from it.

 

After lots of research, I concluded that the APUs should use RAM with the following characteristics and settings:

• Dual-rank modules. 4GB modules are usually dual sided AND dual ranked. RAM specs on AIDA64 can confirm this info. 8GB modules are nearly always dual ranked for DDR3 (at least from my experience).
• Dual-Channel configuration with channel interleaving and bank interleaving enabled (MoBo side).
• No less than 8 GB of RAM.
• Highest possible frequency. 2400MHz for DDR3 is good. More than that is usually too expensive. MoBo must support the OC frequency.
• Lowest possible latency for given frequency. Although the GFXs don't benefit much from this, tighter primary timings are usually coupled with tighter secondary and tertiary timings. Trident X memory modules are a good example of this. Tighter timings will yield better write and copy speeds as it seems.
• Dedicate 2GB to the iGPU

As an example for the significance of RAM performance for the iGPU, with Team Vulcan RAM, after getting the timings as tight and stable as possible, with an OC of the IMC of 100 MHz, Win7 GFXs benchmark scored 6.9 out of 7.9. With the G.Skill memory I went to 7.0 out of 7.9 which translated into about +10% in fps. Also, while with Team memory I could get benefits with an OC of the iGPU up to 850MHz, G.Skill RAM extended the benefit from overclocking up to 900MHz. Basically, the bottleneck limit has been extended.

 

Also, a last, little thing to consider when overclocking the IMC. It is easy to oc it to 1900 MHz from 1800MHz but getting it as high as 2000MHz requires serious bumps in the "NB" voltage. It shouldn't be a problem since the CPU part operates at even higher voltages but, your thermals are gonna suffer from it a lot for what is gonna be two less nanoseconds in memory latency.

 

 

5) Pros and Cons. What makes sense to buy.

 

Since this is already a wall of text, and is only gonna get worse, I'll make lists:

 

Pros

• Great bundle of features.
• Good, reliable performance for basic computing and light gaming.
• Low price for the MoBo with a rich feature set.
• Overclockable.
• Good as a gaming rig if upgraded during its life cycle with a dGPU.
• DX12 compatible and HSA capabilities offer good future compatibility.
• Low power requirments overall.
• Excellent for little, cheap builds.
• Dual graphics with low profile cards is a decent option for slim cases. Can work as a console.

 

Cons

 

• This is basically the best you can get from FM2+. Not really upgradable (CPU wise). Carizzo might be FM2+ compatible but the upgrade expense is a no go if you already own or plan to buy Kaveri.
• Not a good CPU for heavier workloads. It wil run stuff but much slower than an intel quad core.
• IMC creates the whole bottleneck for graphics. Can't change that.
• MoBos which support RAM with higher than 2400MHz frequencies are too expensive to be even considered an option. Marketing gimmicks if you tell me.
• Finding good RAM can be problematic. Buying the correct GPU is much easier for instance.
• Tweaking the BIOS settings to get it to work nicely, can be a long task. On the other hand, just like me, you might like doing this kind of stuff.
• Was too expensive at launch.

 

Models to consider:

 

A10 7850k, for the best gaming experience.

A8 7650k, for good value and good gaming experience on various mainstream titles.

A6 7400k, for affordable, feature rich everyday computing and HTPC applications.

 

The Godavari APUs (A10 7870k and A8 7670k) offer bad value BUT the APU's heatspreader is soldered to the chip. This should make quite the difference in thermals. If they also have indeed better binning, you should get the best OCs with those.

 

EDIT

Thanks to the input of member trucker2, it seems that the A10 7870k offers good value after all. This is due to the large, dual heatpipe, copper plate heatsink AMD bundles it with. That compined with the flux solder of the heatspreader should yield very good results in regards to cooling.

 

 

6) Conclusion. Thoughts about future APUs and possible benefits.

 

The 7850k is indeed a nice piece of hardware. If you set aside the levels of performance on an asbolute scale, this is quite the achievement architecturaly. But what are the benefits from such technology?

 

HSA will offer great efficiency, especially on mobile platforms. It is not that simply by chance Samsung, ARM and others have joined the HSA organization. They probably aim on introducing this technology in phones and tablets as well. But from a PC perspective, what can this offer?

 

With the launch of the Fury lineup this summer, AMD introduced the first commercial product with HBM memory. if they are to extend the usage of this technology on their APUs - and it would be stupid not to do so - they could bring real FHD and maybe even UHD capabilities to their SOCs. Very small form factor systems could be made using hybrid memory controlers, taking advantage of both HBM and DDR4 memory. Although such platforms would not be that cheap, they would probably remove the need of a dGPU for most applications except high-end gaming.

 

Of course, these are all wild assumptions and it might prove impractical to AMD to bring HBM to such a high scale (manufacturing wise). Still, SOCs might provide, compact, power efficient, powerful, silent and neat solutions for most home users. This would bring new, competitive and useful products into the market, and of course, you will be able to run skyrim on those.

 

If you made it this far, I hereby award you the medal of patience, and free time.

 

If you want to correct something or add info, please let me know. Also, input regarding why the IMC is so slow, would be highly appreciated.

 

Thank you!

 

*****************EDIT 6/4/2016***************************

After having upgraded my system with a dedicated GPU, I went on tweaking my overclock on the CPU side. What I noticed though this time around is that any overclock on the IMC, will cause instability at some point, especially with a 20x multiplier. If you are using a Kaveri (probably this applies to a Godavari APU/CPU) as a CPU only, I suggest you do not overclock the IMC at all. Keep it at the default 1800MHz and focus on the CPU side. You are gonna get the most out of your OC that way.

[Guest trucker2]

Awsome review.

The clincher for me was the annandtech review and how well it does with a GTX 770 against cpus costing twice to three times as much. It doesn't win the benchmark but at the price it doesn't have to.

Also It will work with many older PSU's, all you need is standard ATX and a 4 pin cpu connector. The two tierd chipset for the motherboard I also like, 88 for top end and 68 for budget builds. I bought the A68hm from MSI and it was surprised it has the latest pcie, sata and usb specs.

The 7870 has a twin heatpic stock cooler with a quite fan and a copper baseplate. a pleasant surprise.

HSA is also on some of the newer consoles, thus garenteeing implementation in future games. Kaveri implementation is a question mark.

[Guest]

Awsome review.

The clincher for me was the annandtech review and how well it does with a GTX 770 against cpus costing twice to three times as much. It doesn't win the benchmark but at the price it doesn't have to.

Also It will work with many older PSU's, all you need is standard ATX and a 4 pin cpu connector. The two tierd chipset for the motherboard I also like, 88 for top end and 68 for budget builds. I bought the A68hm from MSI and it was surprised it has the latest pcie, sata and usb specs.

The 7870 has a twin heatpic stock cooler with a quite fan and a copper baseplate. a pleasant surprise.

HSA is also on some of the newer consoles, thus garenteeing implementation in future games. Kaveri implementation is a question mark.

 

Oh yeah, good point about that heatsink. Is it any good now? If it is good enough, the higher price on the 7870k might be justified then by overall better thermals. You might even save on an aftermarket cooler.

[Guest trucker2]

[Fattedd]

Very nice review! I like your honest opinion on the APU.

 

The target market seems to be forgotten most of the time, which I think is very important.

[Guest trucker2]

on the right is the 7870, middle is the 7850, on the left is from an emachines AMD single core cpu with an intel style cooler. It is very quite but kinda light. What impressed  me most was the copper base, copper is soo much better then aluminum yet expensive. I trust it better then my T2.

[Guest]

on the right is the 7870, middle is the 7850, on the left is from an emachines AMD single core cpu with an intel style cooler. It is very quite but kinda light. What impressed  me most was the copper base, copper is soo much better then aluminum yet expensive. I trust it better then my T2.

 

That is quite the impressive cooler. With this, I definitely stand corrected. The 7870k seems to be good value after all. Buying it means no worries for the cooling of your APU.

 

And by the way, I updated the post. Thanks!

[Guest trucker2]

Funny story behind the 7870. I planned on an 8320 rig with a nice MB as my gaming rig. But on an impulse when I was by microcenter I got the new 7870 with MSI A68HM-e33 MB cause is was on special for 129 and basically the board was free. No one had reviewed the new 68 chipset boards and I was curious about them. I wanted to build the cheapest pc I could for an HTPC that could also game so when my wife is playing Farmville on my 8320 it would be ok. Played around with it and even used it without a case. Found out the olny hot spot was the chipset w/ a real wimpy heatsink. With my finger on it it felt like a 486 DX/2 50.

    Then my real build goes south. Either bad MB or bad CPU. Pray about it, then I take everything back. Now my impulse buy is my main gaming rig. Swap the 7870 for my dau 7850 to give her a lil speed boost and my new gaming rig is my 7850k with the cheapo MB. The combo still goes for 109 bucks at microcenter. I get some more use out of an old PSU and Case and get to keep money in my pocket.

   MSI has released a BIOS update for my board for the 7870 but refuses to put it on the cpu support list. Instead they came out with a new board, A68HM-E33 V2. Mine is the older one. I still used the overclocking tool in catalyst to bring it to 4.5 before it froze. backed it down to stock where it stays.

My favorite thing about it is I can upgrade when I want to. SSD later on maybe, and for Christmas maybe a GTX 770

 

http://www.anandtech.com/show/9532/the-intel-broadwell-xeon-e3-v4-review-95w-65w-35w-1285-1285l-1265/6

This is actually a broadwell review. Notice how the 7850k with mid-range GPU's goes toe to toe with 400 to 500 dollar cpus from intel. GTA V it does poorly but since I make deliveries to the inner city I really don't want to game there. I can't wait for the new Star Wars Game.

 

I live in Northeast PA, Whitetail country. Kaveri reminds me of the ol 30-30 Winchester. Not super fast like the belted magnums or as accurate as a bolt action with a scope, It just gets the job done.

 

Thank you so much for your review. Man I wish I could post and write that well. I kinda ramble ​

[Guest]

Funny story behind the 7870. I planned on an 8320 rig with a nice MB as my gaming rig. But on an impulse when I was by microcenter I got the new 7870 with MSI A68HM-e33 MB cause is was on special for 129 and basically the board was free. No one had reviewed the new 68 chipset boards and I was curious about them. I wanted to build the cheapest pc I could for an HTPC that could also game so when my wife is playing Farmville on my 8320 it would be ok. Played around with it and even used it without a case. Found out the olny hot spot was the chipset w/ a real wimpy heatsink. With my finger on it it felt like a 486 DX/2 50.

    Then my real build goes south. Either bad MB or bad CPU. Pray about it, then I take everything back. Now my impulse buy is my main gaming rig. Swap the 7870 for my dau 7850 to give her a lil speed boost and my new gaming rig is my 7850k with the cheapo MB. The combo still goes for 109 bucks at microcenter. I get some more use out of an old PSU and Case and get to keep money in my pocket.

   MSI has released a BIOS update for my board for the 7870 but refuses to put it on the cpu support list. Instead they came out with a new board, A68HM-E33 V2. Mine is the older one. I still used the overclocking tool in catalyst to bring it to 4.5 before it froze. backed it down to stock where it stays.

My favorite thing about it is I can upgrade when I want to. SSD later on maybe, and for Christmas maybe a GTX 770

 

http://www.anandtech.com/show/9532/the-intel-broadwell-xeon-e3-v4-review-95w-65w-35w-1285-1285l-1265/6

This is actually a broadwell review. Notice how the 7850k with mid-range GPU's goes toe to toe with 400 to 500 dollar cpus from intel. GTA V it does poorly but since I make deliveries to the inner city I really don't want to game there. I can't wait for the new Star Wars Game.

 

I live in Northeast PA, Whitetail country. Kaveri reminds me of the ol 30-30 Winchester. Not super fast like the belted magnums or as accurate as a bolt action with a scope, It just gets the job done.

 

Thank you so much for your review. Man I wish I could post and write that well. I kinda ramble ​

 

AMD recommends the A88 chipset for A-10 APUs. Could that be the cause of the problem?

[Guest trucker2]

No it was an fx 8320 with a 970 build I was gonna put together that had the problem. Both the 7870 with the 88 mb and the 7850 with the 68 have been drop dead reliable.

[Guest]

No it was an fx 8320 with a 970 build I was gonna put together that had the problem. Both the 7870 with the 88 mb and the 7850 with the 68 have been drop dead reliable.

 

Oh sorry, I misanderstood you.

 

Well, I believe that you will get better performance with the A10 APUs versus the FX since they have higher single thread performance. At least for gaming. The fx though, can overclock more, if you have a VERY good heat dissipation solution.

[PlayStation 2]

like 95% of this can be applied to the 7650k