BleepingComputer.com: Some questions about crossfiring

1. Does it matter if my current card is GDDR5 and the second card is GDDR3? My current card is this and the second card i plan to use is this.

2. Does it matter if it has different clock and memory speed?

3. Do i need to buy 2 crossfire bridge?

4. How stable would it be if i use those 2 cards mentioned in question 1?

5. Would it bottleneck if i used those 2 cards, when running a i5-2500K?

1. The cards are the same series so they should be fine.

2. Same series again should be ok

3. No

4. Keep the drivers up to date and configure it correctly and you should be fine.

5. The CPU should be fine, the only bottleneck I could see happening would be on the PCIE lanes side. You shouldn't worry though

I'd get a second opinion on the first two questions though.

Can you explain what you mean by configuring it?

http://www.hardwaresecrets.com/article/SLI-vs-CrossFire/391/5
This article should answer a lot of your questions about crossfire. I found it a very useful resource.

Very good article. So the faster graphics card will go slower so it can match the slower card speed which i reckon you can overclock the slower card to the same speed as the faster one. So i just need 1 crossfire bridge if there is 2 cards and i would use 2 crossfire bridge if i were to use 3 graphics card.

Actually, crossfire does this thing called dynamic load balancing, where it will balance out what portion of the frame needs to be made by each card. So the faster video card will draw more of the frame than the slower video card, so that they finish drawing the frame at exactly the same time. The faster card won't slow down to the speed of the slower card.

edit:
That's why when using SLI you have to use the exact same cards. Because SLI doesn't have this ability.

This post has been edited by Thumperrr: 13 July 2011 - 09:25 AM

Meh, i still like ATI I am still a bit confused a about the GDDR3 and GDDR5 compatibility. Also i am waiting for a second opinion from someone else too

The memory types shouldn't matter when crossfiring two cards.
Just look up on the ATI site on whether the two cards in question can be crossfired. There should be a list somewhere.

I couldn't find it but i found some other useful info

memory type doesnt really matter as long as the first two numbers match. the first two numbers MUST match or it will not work, i.e. you can crossfire a 4850 with a 4870, or a 4890, but you cannot crossfire it with a 4670. Now, just because they will work does not mean you will have the best results-I crossfired a 4890 with 1 gig of gddr5 with a 4850 with 512m of ddr3-it worked, but I had some texture and driver issues. Still better then a single 4890, but not as good as dual 4890s. So in short, those two cards should work with each other just fine. You only need one bridge, unless your using 3 or more cards. you can put two bridges on, and AMD recomends it, however that being said with my system it actually started freezing my system up on bootup-I had to remove the second bridge. I would start with just the one, but if you have problems theyre only like 5 bucks US, i cant imagine them being much more in AU.

So the only concern here is really about the bridges? Crossfire bridge costs $12AUD which i am going to buy it from here.

I would start with one, Im only using one with my 4890s, and theyre higher bandwidth then the 5670s.

I'm gonna buy 2 because i prefer ordering everything in one go. What do you mean they have higher bandwidth then my 5670?

theyre more powerful cards-they transfer more information between the two. the 5670s may be newer, but performance wise the 4890s will outperform them-just without the directx11 support. The only time, in theory that you should need more then one bridge is if your doing a 3 or 4 way crossfire. On the other note, it doesnt hurt to have an extra bridge laying around as backup. Id also check places like ebay, sometimes its cheaper to buy them used, thats where I got my second bridge if i remember right.

I'll just stick with one site not multiple. So clear it up, that card i chose should work fine and have no driver problems right?