Looking for FM2/FM2+ IGP experts! Hybrid crossfire

[Blue_Max]

Okay, there is a serious lack of info/reviews regarding the FM2 APU's and their hybrid crossfire modes. What they're truly compatible with, the speed increases, the jitters, etc.

There are some basic compatibility charts out there but I believe hybrid crossfire is far more compatible than these charts would suggest.

I believe the APU is capable of more than most people know and would love a serious reviewer (with lots of APU's and video cards to experiment with!) to do something with this!

*hint hint, Anand?* [nudge]

 

[frozentundra123456]

I know Tom's hardware had a fairly extensive review some time ago, but before Kaveri I think. The overall conclusion was that while the framerate was higher with crossfire the stutter was severe enough that the gameplay experience was not appreciably better(I am paraphrasing, but pretty accurately I think). I dont know if this has improved or not. I thought Kaveri was supposed to be much better at this, but you are right, there has not been much attention devoted to it.

TBH though, I can see a place for this in laptops, where you want to keep thermals low by crossfiring a low power dgpu with an apu, and also keep the cost down because laptop dgpus are expensive for the performance they give.

But in the desktop, it just makes more sense in the vast majority of cases to just go with a more powerful dgpu rather than dealing with crossfire issues, IMO.

 

[cbn]

I think this is the article Frozentundra is referring to:

http://www.tomshardware.com/reviews/dual-graphics-crossfire-benchmark,3583.html

P.S. On Kaveri one thing to keep in mind is the cost of a R7 250X (640sp @ 1000 Mhz/GDDR5) vs. R7 250 (384sp @ 1000 Mhz, DDR3). Sometimes the PowerColer R7 250X will be priced lower ($59.99 AR FS = sale price, normal price appears to be $79.99 AR FS) than the R7 250 cards a person will find on Newegg. Now sure why the R7 250 is not discounted the same way the R7 250X is?

 

[coffeemonster]

I bought a 7850K originally with hybrid crossfire in mind. Nothing I read about it after was encouraging enough to buy one of the cards supported. You're right the info on what exactly is supported is hard to pin down. Various forum posts give contradicting answers, I've read only the R7 240 and 250 work, then others say the 250x and 265 work.

Here are various threads of interest on the subject
http://www.overclock.net/t/1465171/no-joy-dual-graphics-on-7850k-r7-250
http://www.overclock.net/t/1458173/amd-a10-7850k-dual-graphics-question
http://www.overclock.net/t/1468461/hcw-radeon-dual-graphics-performance-with-kaveri-and-r7-250
http://www.overclock.net/t/1463049/pcper-a8-7600-and-r7-250-dual-graphics-testing
On the bright side, DX12 is rumored to allow hybrid crossfire with anything, so if you have a more powerful discrete card you'd be able offload some work to the iGPU

P.S. On Kaveri one thing to keep in mind is the cost of a R7 250X (640sp @ 1000 Mhz/GDDR5) vs. R7 250 (384sp @ 1000 Mhz, DDR3). Sometimes the PowerColer R7 250X will be priced lower ($59.99 AR FS = sale price, normal price appears to be $79.99 AR FS) than the R7 250 cards a person will find on Newegg.

yep, the cost of the significantly more powerful cards is probably the biggest hurdle to a dual graphics setup

 

[frozentundra123456]

I think this is the article Frozentundra is referring to:

http://www.tomshardware.com/reviews/dual-graphics-crossfire-benchmark,3583.html

P.S. On Kaveri one thing to keep in mind is the cost of a R7 250X (640sp @ 1000 Mhz/GDDR5) vs. R7 250 (384sp @ 1000 Mhz, DDR3). Sometimes the PowerColer R7 250X will be priced lower ($59.99 AR FS = sale price, normal price appears to be $79.99 AR FS) than the R7 250 cards a person will find on Newegg. Now sure why the R7 250 is not discounted the same way the R7 250X is?

Yes, that is it. I was at work and didnt have time to search for it. Thanks for the link.

And it occurred to me later, if you plan to add a discrete card, it is probably better to go with the athlon x4 and put the money saved toward a more powerful dgpu/

 

[cbn]

And it occurred to me later, if you plan to add a discrete card, it is probably better to go with the athlon x4 and put the money saved toward a more powerful dgpu/

Here is a realistic price breakdown (for Kaveri) going by Newegg prices:

$80 Athlon x4 860k that turbos mostly to 4.0 GHz (in games) plus a $80 AR (sometimes $60 AR) Power color R7 250X (with 640sp @ 1000 Mhz/GDDR5).

vs.

$150 A10-7850K which has a CPU that downclocks to as low as 3.0 Ghz* coupled to a 512sp @ 720 Mhz iGPU (that needs RAM that costs about $10 to $15 more than the Athlon + dGPU set-up mentioned above).

(Both set-ups cost the same amount of money after factoring in RAM)

*When using iGPU for gaming.

NOTE: I compared Athlon x4 860K to A10-7850K because they both have the same advertised CPU clocks. For a lower cost APU set-up, there is the A8-7650K to consider.

P.S. I really hope AMD decides to develop some kind of simple to use utility to combat the CPU downclocking on the various APUs.

 

[Blue_Max]

While T... er... that-guy's article showed a handful of combinations, it's not what I'd call "extensive".

...but it does conclude an important point that makes further testing unnecessary. The increases aren't huge and introduces a stutter so painful it makes hybrid crossfire pointless.

Thank you, though!

 

[NTMBK]

Don't bother even trying with Trinity or Richland. The stuttering was a complete disaster.

Kaveri added XDMA, the same technology which lets Hawaii get super-smooth Crossfire using just the PCIe bus. This lets it do Dual Graphics much more smoothly and consistently, and might make it genuinely worth trying.

 

[SPBHM]

I think AMD also improved frame pacing for Richland/Trinity... they did frame pacing optimizations for stuff as old as the HD 5000 series, once all the FCAT thing happened, so looking at old Richland dual graphics reviews can be misleading

 

[NTMBK]

I think AMD also improved frame pacing for Richland/Trinity... they did frame pacing optimizations for stuff as old as the HD 5000 series, once all the FCAT thing happened, so looking at old Richland dual graphics reviews can be misleading

There's a limit to what they can improve for the older stuff, when the hardware synchronisation method just isn't there. Pre-Hawaii, they needed the Crossfire bridge to get decent synchronisation- Dual Graphics never had that, and the synchronisation was a mess as a result. http://www.anandtech.com/show/7457/the-radeon-r9-290x-review/4

 

[Shehriazad]

I actually had a 7850K + 250 combo for a while. I never had Richland or Trinity before, so I can't speak out of personal experience there...but I didn't really have any problems with stuttering or jittery framerates.

Unfortunately it doesn't just work on any game...and the price/performance doesn't seem to quite fit.

I do have to say that I got myself the GDDR5 version to run it with the Kaveri simply because I used DDR3 ram that was overclocked like mad and didn't want the GPUs own ram to actually be slower. xD

I only tried it because I was able to get both chips heavily discounted...and had the price been better back in the day...it would've been great.

That said....The APU was capable enough on its own if you use some beast Ram. I ran Battlefield 4 @ Medium settings in 1080P and always sat above 30 frames...obviously 60 is what you want to go for as minimum for shooters...but it was impressive enough to have it playable at all on medium.
Games like Warframe even ran completely maxed out with MSAA and always stayed in the 40-60 area with just the APU (actually CPU bound). Now obviously Warframe isn't a high end game...but considering how decent it looks, that was nice.