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6870s in CrossFire

PaulC2K

PaulC2K

PaulC2K

Associate
Joined
4 Mar 2010
Posts
2,127
Looking at upgrading to a pair of these with the special offer going on, and im just wondering whether my 750w PSU (Xigmatek NRP) would be sufficient and stable running 2x 6870s with a Q6600, or whether i'd need 800w or better to run both.
The PSU has 2x 6-pins, im assuming a good old molex convertor is fine for the other 2x 6-pins it'd require, right? (looks like im a 6-pin convertor short, so would need to buy one if they're not included anymore).

Im just looking to get the best performance gains from my existing setup (Q6600 @ 3ghz, 8gb ddr2, and a 5770) without having to spend in other areas because there just isnt the money, and from what i can tell nothing is pushing the CPU that hard anyway, the GPU has always been the limiting factor. Im also running at 2048x1152 so pixel pushing power is a must, and this seems to far outperform a 6950 which is the only other option in my price range from AMD.

Havent done crossfire before, are there any pitfalls or things i should know before plunging in head first? I know some games dont always like CF, so might be reduced to a single card, but are there other issues i havent read about?
 
PaulC2K said:
Looking at upgrading to a pair of these with the special offer going on, and im just wondering whether my 750w PSU (Xigmatek NRP) would be sufficient and stable running 2x 6870s with a Q6600, or whether i'd need 800w or better to run both.
The PSU has 2x 6-pins, im assuming a good old molex convertor is fine for the other 2x 6-pins it'd require, right? (looks like im a 6-pin convertor short, so would need to buy one if they're not included anymore).

Im just looking to get the best performance gains from my existing setup (Q6600 @ 3ghz, 8gb ddr2, and a 5770) without having to spend in other areas because there just isnt the money, and from what i can tell nothing is pushing the CPU that hard anyway, the GPU has always been the limiting factor. Im also running at 2048x1152 so pixel pushing power is a must, and this seems to far outperform a 6950 which is the only other option in my price range from AMD.

Havent done crossfire before, are there any pitfalls or things i should know before plunging in head first? I know some games dont always like CF, so might be reduced to a single card, but are there other issues i havent read about?
Click to expand...

750W should be fine and molex converters do the job. But why don't you look at 2 x 6850 instead? They run cooler and quiter without taking too much of a knock on performance
http://www.anandtech.com/bench/Product/301?vs=302

I'm busy setting up crossfire for the first time on 6850's. Your case's cooling ability will be quite important now. Ideally front, back and top fans. Or if you can fit a side fan that will help a lot. I'm still experimenting myself though.

I can't really comment on the CPU but some games are more CPU dependent than others, so you might want to look at some CPU benchmarks. Not sure if it will cause a bottleneck for crossfire. Hopefully others can comment.
 
I'm also in the same boat but my 1000W PSU should suffice, I do have other questions however. Am I O.K with installing the display driver only like I have been doing with my 5970? I'm assuming XFire will work fine like it did. Do I need to use two XFire bridges or will the 1 suffice?

Thanks.
 
rocsen said:
750W should be fine and molex converters do the job. But why don't you look at 2 x 6850 instead? They run cooler and quiter without taking too much of a knock on performance
http://www.anandtech.com/bench/Product/301?vs=302

I'm busy setting up crossfire for the first time on 6850's. Your case's cooling ability will be quite important now. Ideally front, back and top fans. Or if you can fit a side fan that will help a lot. I'm still experimenting myself though.

I can't really comment on the CPU but some games are more CPU dependent than others, so you might want to look at some CPU benchmarks. Not sure if it will cause a bottleneck for crossfire. Hopefully others can comment.
Click to expand...

Sorry to correct you but 2x6850's are noisier and hotter than 2x6870's according to those benchmarks.
 
buchtis said:
I'm also in the same boat but my 1000W PSU should suffice, I do have other questions however. Am I O.K with installing the display driver only like I have been doing with my 5970? I'm assuming XFire will work fine like it did. Do I need to use two XFire bridges or will the 1 suffice?

Thanks.
Click to expand...

How many cards do you want to run? And do you mean the display driver only without CCC? Crossfire requires CCC, it's the only way to enable it AFAIK
 
rocsen said:
How many cards do you want to run? And do you mean the display driver only without CCC? Crossfire requires CCC, it's the only way to enable it AFAIK
Click to expand...

2 6870's. Thing is the 5970 had just the display driver installed and XFire was enabled but then again that's 2 dies on 1 PCB, would having 2 separate cards require me to install CCC?
 
rocsen said:
750W should be fine and molex converters do the job. But why don't you look at 2 x 6850 instead? They run cooler and quiter without taking too much of a knock on performance
http://www.anandtech.com/bench/Product/301?vs=302

I'm busy setting up crossfire for the first time on 6850's. Your case's cooling ability will be quite important now. Ideally front, back and top fans. Or if you can fit a side fan that will help a lot. I'm still experimenting myself though.

I can't really comment on the CPU but some games are more CPU dependent than others, so you might want to look at some CPU benchmarks. Not sure if it will cause a bottleneck for crossfire. Hopefully others can comment.
Click to expand...

I did ponder the 6850s, but at a saving of a tenner :eek: wont be paying £115 at least not while the 6870s are £120.

'Cooling' uggh :D
My current case situation is leave the side off and stick 2x2 120mm fans zip-tied together to blow air onto the chipsets and over the ram, gfx etc. The case is in a cupboard which is basically the space above the stairs, so its about 1.5 x 1.0 x 1.5 meters in size, split in 2 (PC downstairs, Microserver & PS3 upstairs) and just a small hole in the far corner for cables to allow heat out which is far from ideal.


Im currently reviewing things, possibly purchasing a new CPU/Mobo/RAM bundle (2500K vs 1090T), and hopefully getting in on the 6870 action before the price bump if i can get rid of some junk i should have got rid of ages ago and free up some cash. The main game of interest is the Battlefield series, and currently BC2 is nailing my GPU and comparitively the CPU is sat back begging for something to do. BF3 may well change that, and i'd suspect having 2 improved GPUs pushing the visuals it will allow the CPU to deal with more too, if the GPU bottleneck is opened up.

Snubber said:
Sorry to correct you but 2x6850's are noisier and hotter than 2x6870's according to those benchmarks.
Click to expand...
Thats rather surprising tbh.

Thanks for the assistance guys
 
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