[Solved] ATI Radeon 2x4650 Crossfire worse than 1x4650

Hi everyone,

I've read a number of topics on the subject but none have been able to help. I used to have 1 ATI Radeon 4650 and recently bought another. I plugged it in, enabled crossfire in CCC, launched some games to test the setup and NADA - they lag immensely and the overall performance is significantly worse than that of just my old 4650.

Please give me some ideas as to what to do...

Also, ìf this is useful at all, I'm running:

•Windows 7 32-bit
•AMD Phenom II X2 555 Processor (2x @ 3.2GHz)
•4 GB RAM
•Motherboard: Gigabyte 890GPA-UD3H
•I can give the GPU-Z stats if necessary for both cards

Is one DDR2 and the other DDR3 by any chance?

Seeing as the DDR3 one has to slow down to the speed of the DDR2 one, yes. On a low end card like those I wouldn't think the ram would make that much difference, but if you say so...

^+3

But why 2x HD4650? you will better with a single powerful card like 4850 or even HD5770...

Number 1 rule in Crossfire or SLI, 2 low end cards will still give you low end performance, that is all there is to say about that. They may improve performance, but the performance improvement is not always somewhere you will see it. For instance, I am sure that higher res gaming is improved, but you have to be relevant about it. Sure enough, if you are gaming at 1920x1280, and you are only getting 10fps with your 4650, adding another might get you to 20 fps, which is still terrible. If you are gaming at 1280x1024, or less, then adding another card for won't do much for you anyway, at those resolutions, you simply need a more powerful card if 1 card isn't doing it. Crossfire and SLI can be very beneficial, but you have to take other things into consideration.

Just to add something, you need to download from ATI the Crossfire Profiles.

And make sure to only use 1 crossfire bridge. If you use 2, it can cause issues.

Also make sure you have your CCC 3D settings set to "use application settings" in all the relevant areas, and try Catalyst A.I. on either Advanced or Standard.

Also, might be worth trying different driver versions. If you're on 10.6, try 10.4. Or update to 10.6 first if you're not currently using them.

You need to have a physical crossfire bridge to connect the cards to gether. Unless you were talking about a 4650x2 single card, in which case DDR2 vs DDR3 issue doesn't make sense since it's one card. I'm assuming therefore you have 2 discrete cards. To crossfire them, you must use one of these:


And also activate CF in CCC.

You don't need the bridge because low end cards like this "talk" through the PCIe bus. No higher speed link is needed.

If you want to test, try this. Use fraps and record what your DDR3 card can do by itself. Switch cards and see what the DDR2 card can do. Remember that you will at best double THIS score. If your DDR3 card can do 30FPS, while your DDR2 card can only do 12FPS, you don't get 42FPS (30 + 12), but 24FPS (12 x 20. This is bad ofcourse because it's worse then what the DDR3 card can do by itself.

If you are using such a high resolution then I'm not surprised the drop in memory bandwidth is making performance worse despite 2 cards. 128 bit + DDR2 simply has no business trying to move the kind of data necessary for gaming at 1920x1200.

You could try OCing it, but I doubt it would help much. Single DDR2 card was 9-14FPS, or around 12FPS. Adding another card would at best double it, so your looking at around 24FPS. This is consistent with what you were seeing in CF. I would say everything is working fine.

So what to do? First, return/sell the DDR2 card. As you've learned there is no point in slowing down the faster card. You might also want to sell the DDR3 card and use all that $$$ to buy a single faster card. A 4650 really isn't the card you want for gaming at 1080/1200. To really max everything out you'd want the 5850 which I'm assuming is more then you want to spend. I'd consider getting the 5750/5770. Should be around $100-$150 if you buy online, and will make most everything look good.

Thanks a lot for your help everyone!

I guess that is what I will do then - sell these two and then get a temporary replacement in the form of a 5750+ (what I really wanted to do was hold out for the new 28nm cards but that might be too long of a wait to endure with a single 4650, albeit a GDDR3 one...)

Thanks again for all your tips and help in resolving all this!

Best answer selected by lucky-nz.