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Fitting 2x ASUS Radeon HD 6950 DirectCU II in a case. Is it possible?

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September 13, 2011 2:22:52 PM

So, I have spent some time planning out my new rig. It is gonna look like this:

CPU: Intel i5-2500K
GPU: 2x ASUS ATI Radeon HD6950 DirectCU II 2GB in CrossFire
Motherboard: ASRock Z68 Extreme3 Gen3
RAM: G.Skill Ripjaw X DDR3 PC12800 1600MHz (2x4GB) 8GB
PSU: OCZ GameXStream 850Watt
Case: Antec P183
HDD: Western Digital 500GB 7200RPM


Now, I didn't notice this until today, but the ASUS HD 6950 DirectCU II GPU's take up 2.5 slots! I had really set myself up to getting two of these cards, especially for the great cooling and silent operation. Is it even possible to fit these two cards in this motherboard or the case at all? If not, is there any motherboard or case that would handle both cards, at around the same price?
Or is the better way of going about it, simply to get another brand of the 6950?
a b B Homebuilt system
September 13, 2011 2:34:55 PM

imo, the best way is to get a different model of 6950. while they will fit together on the asrock extreme3, they will be sitting right up against eachother, negating the benefits of the large heatsink. and, as you have mentioned, youll have to find an appropriate case - its simply not worth it as there are plenty of good hd6950 models.

my choice would be the sapphire hd6950 2gb, which is very well priced and has a solid dual fan cooling system:
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
but if you want something a little more "premium", the MSI twin frozr iii is superb:
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...

i think youll be better off with a 1tb hdd if you dont already have it, theyre actually faster:
http://www.newegg.com/Product/ComboDealDetails.aspx?Ite...
a b B Homebuilt system
September 13, 2011 3:24:12 PM

The motherboard has a 3-slot gap so they will fit in fine. However as posted above, this COULD cause some heat issues especially since the case you have doesn't have a side fan blowing cool air directly onto your GPU's.
Related resources
September 13, 2011 3:30:06 PM

Still, the GPU's would be right up against each other, if I understand correctly. And the top card would get pretty hot.
Starting to think the best idea for around the same price is going with the Sapphire cards, since I'm also worried there won't be enough space in the P183 case for the two ASUS cards having only 7 expansion slots. Not sure if I got this right though :) 
a b B Homebuilt system
September 13, 2011 4:45:32 PM

That's why it's ALWAYS better to go with 1 faster card. Besides with the micro-stuttering, I don't know who would want it.
a b B Homebuilt system
September 13, 2011 5:29:27 PM

Or a bit of modding to the P183, 2x 120mm gfx cooler fans on the side door,
I love the Asus 2Gb as well and would rather work round any issues than take another brand
Moto
September 13, 2011 5:36:00 PM

first thing i notice is that the motherboard you've chosen will not let you use two pci lanes at x16 simultaneously. imho, this is essential if you want to take full advantage of a dual-card setup.

you could go for this motherboard:
in addition to x16/x16 at the same time, there is a lot more space between pci lanes, for better cooling (make sure you buy the extra long crossfire bridge.)

alternatively, you could get a HD6990 and stay with the motherboard you've chosen. you would get the dual-gpu performance via x16 connection since you would only be using one pci slot. in my opinion this is your best option.

either option is ~$150 more than your current setup.
a b B Homebuilt system
September 13, 2011 5:44:25 PM

The Asus 2Gb 6950 comes with the longer bridge, they figured you need it :p 
your link isn't working btw, but yes 16/16 is a must, if you're forking out wedge for the cards you can't skimp on the board lol
Moto
a b B Homebuilt system
September 13, 2011 6:59:30 PM

It is not necessary to get a board with dual x16 PCIe slots because plenty of reviews have shown that the difference in performance between dual x8 and dual x16 on PCIe 2.0 is ~5%.
Secondly the Asrock Z68 Extreme4 Gen3 is supposedly a PCIe 3.0 compliant motherboard. Dual x8 on PCIe 3.0 has equivalent bandwidth to dual x16 on a PCIe 2.0 link, so if the motherboard truly is PCIe 3.0 compliant then it won't lose that ~5%.
a b B Homebuilt system
September 13, 2011 7:27:43 PM

True that 8/8 is close enough, but I would see it like buying a expensive top-range car then fitting less than topnotch tyres on it :) 
not essential, just a nice touch
Moto
September 13, 2011 7:34:30 PM

Hey dude when going crossfire or sli its best to stay with the reference designs, believe me! Just make sure there is one slot space between them
September 13, 2011 7:52:25 PM

Wow, thanks for all the replies guys!
So, since the ASRock motherboard has PCIe 3.0 compliancy, and I wouldn't mind running 8/8 on PCIe 3.0 if I got the Antec P193 which has a 200mm intake fan on the left side of the case, which would effectively cool the GPU's, wouldn't that work out, without the top GPU getting too hot? Will the case and motherboard be able to take this?
September 13, 2011 8:19:02 PM

the hd6950 is only pci-e 2.1 so umm... unless i am severely mistaken, you won't see pci-e 3.0 speeds with that card, even if you are in crossfire. someone correct me if i'm wrong. the next gen radeons (7000 series) should be pci-e 3.0

my link above works for me, but if its not working the board i was recommending is the extreme7 gen3:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

still think you should consider a single-card solution...
September 13, 2011 8:30:50 PM

aaaaaand on top of that, sandy bridge doesn't support pci-e 3.0.

you would need to wait and get an ivy bridge processor if you really want pci-e 3.0 support.

i really wouldn't bank on 3.0/x8/x8 making up for the speed loss compared to 2.0/x16/x16 when neither the cpu or gpu supports it :) 

September 13, 2011 8:30:59 PM

Hm, yes you are right. I'm kind of a noob, so forgive me for making assumptions :) 

I've been running CrossFire since I got my 3870's in early 2007 so my idea for my new setup was initially a single-card solution.
However, since I'm used to the issues concerning Crossfire, and I think the gap between 2xHD6950 and the HD6990 is pretty huge, price-wise I ended up choosing the Crossfire alternative.
a b B Homebuilt system
September 13, 2011 8:35:30 PM

please look at the benchmarks that i have already linked:
http://www.tomshardware.com/reviews/p67-gaming-3-way-sl...

Any p67 or z68 mobo that claims to have x16/x16 has an NF200 bridge. As you can see in the above article, the performance difference between p67 x8/x8 and p67+nf200 x16/x16 for 2x hd6950's in crossfire is less than 1% at 1080p.
September 13, 2011 8:52:35 PM

genghiskron said:
please look at the benchmarks that i have already linked:
http://www.tomshardware.com/reviews/p67-gaming-3-way-sl...

Any p67 or z68 mobo that claims to have x16/x16 has an NF200 bridge. As you can see in the above article, the performance difference between p67 x8/x8 and p67+nf200 x16/x16 for 2x hd6950's in crossfire is less than 1% at 1080p.



I'm not gonna call myself an expert, and I might be completely wrong. But the way I read that chart, is that the bottom card is always the control, since it's always 100%. So, what it shows is the increase from the X58 x16 until the P67 with the NF200 bridge. I have a hard time believing that a setup with three GPU's with X58 NF200 x16/x16/x16 performs only 0.24% better than a single 6950 card on X58 x16.

Please tell me if I have COMPLETELY misunderstood that chart and I'm totally wrong.
As I said to begin with, I can't call myself an expert, I'm just trying to understand :) 
a b B Homebuilt system
September 13, 2011 9:01:25 PM

you are correct. you can also just look at the framerates from the individual games, which are on the previous pages in the article. i linked the article for the one comparison only: 2x hd6950's p67 x8/x8 vs p67+nf200 x16/x16 at your resolution, which i am assuming is 1080p.
September 13, 2011 9:03:45 PM

I think I missed your original point.
I'm gonna try again:
So you're saying if I got the ASUS cards and put them in the x8 PCI ports, rather than the x16 ports I could put other brands in, I would only lose those few percentages?
September 13, 2011 9:06:29 PM

word. i was looking for an article like that; assuming the performance gain would be more like 8-10%

i've only ever used true crossfire setups on amd 790/890fx and i could tell a huge difference.

that being said, OP would avoid the whole issue and reduce heat+energy use, by getting the hd6990, and it would futureproof it just a tad. you're already spending like $1400 give or take, the extra $$ might be worth it. i don't think the i5-2500k would bottleneck the hd6990, although im sure tom's has an article on that somewhere...

p.s. i think i am assuming you will use this rig for eyefinity or at least 1900x1200 gaming, because otherwise you don't really even need a second hd6950, just get a single hd6970 or better yet, track down an hd5870 and use it until the 7000 series arrives.
a b B Homebuilt system
September 13, 2011 9:12:37 PM

my point is the same as it was in the first reply in this thread.

i linked the article in order to show that you dont need to spend $150 to upgrade to an x16/x16 board, despite what others have said.

September 13, 2011 9:13:08 PM

Ah okay, now I think I get it :) 

I just think the gap between 2x6950 and a 6990 is quite big, I'm a bit economically challenged at the moment, but my old rig is starting to fail when it comes to newer games. So I can't really push it much further than around $1300 (This is without the HDD and PSU, that I already own).
I generally have a policy of revamping my computer around every 3 years. Having a savings account specifically for this, so I'm looking for this setup to keep me stable for at least three more years.
September 13, 2011 9:18:24 PM

So, overall would it not be worth it to get the ASUS cards, the ASRock Extreme3 and then upgrading to the Antec P193 which has an intake fan directly pointed at the GPU's rather than spending ~$150 on a 6990 or an Extreme7 motherboard?
September 13, 2011 9:47:42 PM

Basically, if you buy the Extreme7, you will be spending 130% more for just ~5% improvment (in the pci-e lines). IMO a single 6950 is more than enough if you are not doing eyefinity. And also remember that radeon hd 7xxx series are near. So I would save the money of the second 6950 and upgrade when they come out.
September 13, 2011 9:57:16 PM

I'm currently only running a single monitor at 1920x1200.
If I bought a single 6950 or even a single 6970 now and waited for the 7xxx series, I'd still only have the money for a single card by then if I upgraded. I'm just worried that it will hold up for at least three years with a single card.
I don't really plan to upgrade my parts along the way, as much as I plan to keep the rig as it is for a three year period and then completely revamp the system, this is what I've done for a long time already :) 
a b B Homebuilt system
September 14, 2011 7:18:32 AM

Thats the whole point. Buy the single most powerful GPU you can afford now in your initial build. And then when you notice performance "struggling" or not running games on enthusiast with 40+ fps, slam another card in. Buy a single 6970 now, in 6months-a year or whenever, slam another 6970 in crossfire into your build. Prices will have dropped significantly by the time you will need a second card and running x2 6970's is going to provide some killer performance on as many monitors as you wish :D 
September 14, 2011 12:55:12 PM

AdrianPerry said:
Thats the whole point. Buy the single most powerful GPU you can afford now in your initial build. And then when you notice performance "struggling" or not running games on enthusiast with 40+ fps, slam another card in. Buy a single 6970 now, in 6months-a year or whenever, slam another 6970 in crossfire into your build. Prices will have dropped significantly by the time you will need a second card and running x2 6970's is going to provide some killer performance on as many monitors as you wish :D 


That does sound like a good plan. I think I just might do that :) 
September 14, 2011 2:44:27 PM

If I were OP Id get a single 6950 or gtx 570, end of story
a b B Homebuilt system
September 14, 2011 2:53:42 PM

jjb8675309 said:
If I were OP Id get a single 6950 or gtx 570, end of story


Not sure if you typed it wrong, but 6950 = GTX 560Ti, and 6970 = GTX 570
September 14, 2011 3:20:01 PM

well being that the OP already has a single 6950 then Id just roll with that

gtx 560ti=6950, gtx 570=6970 im on board with that
a b B Homebuilt system
September 14, 2011 3:22:12 PM

oh right, yeah just shove another 6950 in then if you already have one. they will provide more than enough performance for all games currently released and most future games as well for a good while.
September 14, 2011 3:25:55 PM

^yeah personally id stick with a single gpu but if dual 6950s is the desire then it will fit but temps will need to be kept in check... or at least the OP should be cognizant of what they are
September 14, 2011 3:27:12 PM

True, I plan on getting a 6970 now and purchasing one later, as well as getting the Antec P193, which has a fan blowing directly at the GPU's for more manageable GPU temperatures :) 
September 14, 2011 6:19:48 PM

sounds good, that will be a solid setup...
May 21, 2012 4:09:16 AM

What's the best place to get the lowdown on the theory and application of PCI bus lanes?
!