Crossfire Question: Use 2 different models of the same card (6950)

Everything you ever wanted to know about crossfire

this chart shows the cards you can crossfire

u need another 6950 but make sure that the other one have same clock speed otherwise reference card default speeds 800 mhz if u bought 825 mhz card the other 825 mhz will be downclock upto 800 to perform same as crossfire set it default rate of both card into 800mhz

You can crossfire 2 6950's, but if you have a card with 1GB of RAM and one with 2GB of RAM, you will not have 3GB of RAM. Crossfire will use the amount of memory on the lowest card. Hence, with 2 cards, you will have 1GB of RAM. Which should not at all be a problem.

Also, 1 6950 should be able to run 3 monitors. And that chart posted above shows you what you can crossfire together.

What power supply do you have?

Can you please explain what you mean when you say you have a cheap 512MB Radeon for you 2 other displays?

I broke the MOBO twice on my machine when re-arranging wires and kind of lost faith in myself working with the computer, So I took it into the local computer shop and they added a $50 AMD Radeon into it. Here's the specs from GPU-Z on it.

Name: ATI Radeon HD 5400 Series
GPU: Park
Release Date: Jan 7,2010
Memory Type: GDDR3
GPU Clock: 650 MHz
Mem Clock: 667 MHz

(the whole reason I did this was because I didn't know about the Displayport converters at the time, but its nice to have since the card powers the 2 monitors fine and I want everything I can get on my main display, and my single HD6950 doesn't seem to be cutting it as it is.

500W. I understand I will need to upgrade, what should I upgrade to if I get another card? I was thinking 750W-800W but I dont want to be short on any rate of power, since I do overclock to some extent, so 50W-100W spare at all times would be nice.

Also: Why does the crossfire take from the lowest memory? shouldnt it go from the highest if it's going to crossfire? What happens to the other 2GB if I do decide to do this?

Based on that it looks like I'm getting another 6950, because Newegg has no 6990's an the 6970's are way expensive (I really only buy from newegg)

Also: One mine it says external bridge required, what exactly does that mean? I didn't see much about it on that post you linked.

Well it will just take 1GB from both of the cards. Honestly, I have no clue why, but that's just how it is.

And with a crossfire 6950 setup, I might recommend a nice 750W or 800W PSU.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Here's a variety of units that should work fine.

any decent card should come with one, some higher end mobo's too.. Youre current card came with one but not youre mobo

Hmm.. Don't remember that. I guess I'll just buy another 1GB model of the HD9650 and use the bridge that comes with it.


Another issue: What card should I get?

My current card's clock rate is the following:

GPU: 870, OC's in ccc to 900MHz
MEM: 1250MHz, OC's in ccc to 1325MHz

I need to decide which GPU to get now, since the one I have above is no longer sold, there are still 5 HD 9650's on Newegg selling though,

http://www.newegg.com/Product/ProductList.aspx?Submit=E...

Which one of these should I get? Note that only 1 card left is actually 1GB aswell, so it looks like I'm probably going to be wasting a GB  

Also: I know that if I get a 2GB, 1GB will be unused, but since it's still combining 2 1GB GPUs, would it bump the RAM up to 2GB or no?

Well keep in mind to get optimal results the cards must be clocked the same. And if you want to wait a bit that Sapphire 6950 goes on sale for $200 quite often.

physically you will have 2gb of ram, one gb per board. Pratically you will only have one gb because the memory on both boards needs to contain identical data in their ram. effective you have 1gb of data stored twice.

Thanks, I'll wait for it, also, does my motherboard (it's in the first post) support 3 GPUs?

Looks like it only supports 2.

More questions ..

What games are you running that are taxing your 6950 so heavily?

Minecraft, Skyrim, GTA4.

GTAIV even runs slowly on my computer. Its really really poorly coded from the console. I can barely pull 60 frames.

Skyrim should run fine, and Minecraft as well.

Not minecraft when you add those texture and GLSL shader mods. I get maybe 100FPS with the minor water shader and with the GLSL shaders maxed out its like 30, and I need to be able to record with fraps in those conditions.

Well you could get another 6950, but be sure to get a better PSU for sure.

So I am going to start by saying that I am not against you getting another 6950 to use with games. I have a 6950 as well and have thought many a time about setting it up in crossfire.

However, the flip side of things is that if you are looking to pull great frame rates from games that are maxed out graphically you have a long and tedious road ahead of you. It is a hard thing to do to buy hardware now that will max out games of the future.

In all honesty the only thing that has kept me from doing crossfire myself is the fact that the 6900 series is almost 2 years old now. You may be better off picking up a 7900 series card and attempting to sell your 6950. You will see better performance and lower power consumption so you won't have to replace your PSU or at least you won't need a monster PSU.

I just don't see the value in sinking money into old tech, especially as prices are dropping (and performance is going up) on the new tech.

I had been planning on using the 6950 as my secondary card and my new primary as a EVGA GTX 680 4GB model, but I hear they are releasing a new series very soon...?

Anyways, I went up to the guy that first helped me get the parts for the computer, and he recommended saving money and crossfiring.

How would you use a 6950 as a secondary card and a 680 as the primary? Dont get that part.

Whether you want to crossfire or get new cards is your call. It seems as though youve heard both sides of the story here.

Use the 6950 to support my 2 secondary monitors instead of the other card I have.

I guess that makes sense, but thats alot of power you're using.

Yeah, power isn't a huge deal where I am right now, but I will need a new PSU, I was thinking a 750W-900W PSU for 2 high powered GPUs + overclocked intel i5