Some Crossfire questions

[DotFifty89]

I have never used two gpu's in one system before, so here are some questions:

What would be better, 1 7970 or dual 7950? Im pretty sure it's 2 7950's but how is it better?
And is it worth the price difference?

I have read there are sometimes problems with SLI/Crossfire configs. Were the game stutters? Because the gpu's are running at seperate times? Not sure if I read that wrong somewere. Are there any known problems when using two gpu's? Any upkeep of some sort?

when installing the graphics cards, the bottom gpu has the other right on top of it, so how does the bottom one have any airflow?

I have never looked into using this sort of configuration so I don't know much anout it, I apoligise if I have asked any questions that have been asked numerous times before. Thanks for any input

 

[Orangey]

I will attempt to address this point by point

Dual 7950s give better performance by a mile, especially when overclocked. At current (clearance) prices it is worth it.

AMD recently released drivers that greatly reduce the microstuttering as much as technologically possible and are continuing to improve said drivers. Nvidia have had this "frame pacing" technology (as it is called) for a while. Basically you should not worry about that issue any more. As far as other issues re: multiple cards - game support, heat and airflow, PSU requirements, CPU bottlenecking.

-Some games (Rome 2 for example) do not support more than 1 GPU in any meaningful way. But this is now rare.
-You will need roughly a good 750W power supply (Corsair, Seasonic) or more.
-Your CPU can "bottleneck" your multi GPU system by not keeping up. For 2 7950s, for example, an Intel i7 2600K overclocked to 4.5GHz+ is required for games like BF3 and Crysis 3. Other games seem to do fine with a 2500K (no hyperthreading). Otherwise your GPUs will top out at less than 100% usage.

So basically you need plenty of airflow (roomy case, lots of fans or high rpm fans) and ideally a decent gust blowing directly through the 2nd GPU. A lot of new cases accommodate this in their design, but you can position a fan for this purpose yourself using cable ties and such. It may not be necessary however.

 

[DotFifty89]

Thanks a lot for the detailed reply, helps a lot.

Im currently thinking of this spec:

Corsair 350D case
I5 4670k
Asus Maximus Gene mobo
2x 250gb Samsung Evo SSD
2x HIS 7950
Psu - Undecided but currently looking at Corsair ones
Corsair H100i Cooler
Corsair SP 120 fans x 3

 

[tommybhoy]

If you swap out the Asus Maximus Gene for something less bling like a MSI Z87-GD65, you can up the cpu to a 4770K.

Don't skimp out on the case if you are going dual gpu, you want one with good airflow, P280 is what I use and you can fill it up with fans.

Seasonic produce Corsairs psu's, so take a look at them too.

I swapped out the H100i corsair fans(plain SP120's???) for Akasa Piranha's- they are a little bit quieter while pushing more air.

 

[LtMatt]

I will attempt to address this point by point

Dual 7950s give better performance by a mile, especially when overclocked. At current (clearance) prices it is worth it.

AMD recently released drivers that greatly reduce the microstuttering as much as technologically possible and are continuing to improve said drivers. Nvidia have had this "frame pacing" technology (as it is called) for a while. Basically you should not worry about that issue any more. As far as other issues re: multiple cards - game support, heat and airflow, PSU requirements, CPU bottlenecking.

-Some games (Rome 2 for example) do not support more than 1 GPU in any meaningful way. But this is now rare.
-You will need roughly a good 750W power supply (Corsair, Seasonic) or more.
-Your CPU can "bottleneck" your multi GPU system by not keeping up. For 2 7950s, for example, an Intel i7 2600K overclocked to 4.5GHz+ is required for games like BF3 and Crysis 3. Other games seem to do fine with a 2500K (no hyperthreading). Otherwise your GPUs will top out at less than 100% usage.

So basically you need plenty of airflow (roomy case, lots of fans or high rpm fans) and ideally a decent gust blowing directly through the 2nd GPU. A lot of new cases accommodate this in their design, but you can position a fan for this purpose yourself using cable ties and such. It may not be necessary however.

Spot on.

 

[Drangueos]

If you swap out the Asus Maximus Gene for something less bling like a MSI Z87-GD65, you can up the cpu to a 4770K.

Plus you will have more space between the cards, so the top card will get more air.

 

[flopper]

What would be better, 1 7970 or dual 7950? Im pretty sure it's 2 7950's but how is it better?
And is it worth the price difference?

I have read there are sometimes problems with SLI/Crossfire configs. Were the game stutters? Because the gpu's are running at seperate times? Not sure if I read that wrong somewere. Are there any known problems when using two gpu's? Any upkeep of some sort?

Thanks for any input

Depends on resolution, if you play at 1920x1080 I would buy one single 7970.
If you play with 2560x1600 or such then crossfire is a good option even though a single 7970 works with drop down visuals in games like Bf3, many other games can still play often maxed out.
There is a learning curve with crossfire as if you play many different games then single gpu is often a better hassle free option and again depends on what games and how many you play.

My personal choice playing at 5040x1050 120hz is one single 1200mhz OC 7970 due to I rather lower settings in games for a higher fps rate like BF4 than to go for a crossfire solution. I would assume if you dont use eyefinity then crossfire is also likely to work better since the requirements are lesser and few things can go wrong with single screen. In BF3 I have 80+fps with my set up even though I use low settings it shows what is doable and possible if you dont the max out settings.

I did read about a guy here in sweden with trifire 3x7970 and he was really happy with his set up with the new driver for framepacing as for him it works flawlessly now with single screen.

since I mainly play upcoming BF4 or as such rts/rpg from time to time like diablo3 which I play maxed out, I am happy with this set up.
the upcoming 9970 (290x) might even adjust the playing field a bit.

still, 2x7950 is by far price/performance ratio, unbeatable.

 

[DotFifty89]

Cheers flopper. I think I will be putting a hold on the gpu to see what the new series of amd holds, will then either get a current gen for cheaper or buy one of their newer ones depending on the price.

Are these going to be officially revealed on September 25th?