new to crossfire

547 Views 10 Replies 8 Participants Last post by u238, Mar 16, 2009

Sharx

Discussion Starter · Mar 16, 2009

Ok, so I just built my first system and like Im sure everyone was, am looking to make upgrades immeadiately.

So one of the things that I was looking to upgrade was my graphics card. I dont want to replace it, but want to crossfire it. But theres a few things that I dont know about what I need/what I need to do.

1. Do I need to have an exact same 2nd gpu in order to crossfire?
2. If no to #1 can I crossfire a 4870 with a 4850 without complications
3. I have a 700 watt Kingwin psu with multiple pcie connectors, one used. Do I need to upgrade the psu in order to have 2 4850's/other gpu's?
4. I have a GA-EP45-UD3P mobo and know that the 2 pci-e 2.0 slots go to 8x on each lane for a crossfire. How exactly does this affect it and is it detrimental?
5. If I crossfire, will I be limited in the ability to not watercool the two gpu's later on when I switch to water cooling?

Thanks for the help.

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sav5716

· #2 · Mar 16, 2009

1) I think it has to be identical but the poster below has different info...
2) I didn't think so, but yes, apparently it would work, I learned something too.
3) I think Kingwin makes good PSU's so you should be fine?
4) It will slow down the card but it won't affect it so bad that it makes the purchase not worth it.
5) You may not have enough room to water cool both, I'm not sure. Then again, I know nothing about watercooling.

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igob8a

· #3 · Mar 16, 2009

You can use different GPUs just from the same series (4000 series in your case), so a 4870 will crossfire with your 4850.

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sav5716

· #4 · Mar 16, 2009

Quote:

Originally Posted by igob8a

You can use different GPUs just from the same series (4000 series in your case), so a 4870 will crossfire with your 4850.

When did this happen!

My bad, sorry for the bad info.

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AMOCO

· #5 · Mar 16, 2009

Like they said

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Asus Mobile

· #6 · Mar 16, 2009

Quote:

Originally Posted by sav5716

When did this happen!

My bad, sorry for the bad info.

No you said it! Same chipset, why you posted 4850 and 4870 are different? I don't know, maybe information overload. Happens to the best of us, and also the trolls?

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mocha989

· #7 · Mar 16, 2009

You will loose 5 to 10% of your performance on a P45.

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Sullivan

· #8 · Mar 16, 2009

Which I hear is very unnoticeable, you will be fine, I plan on crossfire-ing soon.

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mocha989

· #9 · Mar 16, 2009

it is quite noticable with 4870s not as noticable with 4850

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Sharx

Discussion Starter · #10 · Mar 16, 2009

Alright, thanks for the tips about the compattibility and the 2 lanes of 8x. The only question though that I am not sure of is how the power works for a single graphics card as opposed to crossfired gpu's. I was told that my gpu would need at least 450 watts. What I never understood was would I need double that in order to run 2 of those gpu's or is there a different way of determining how much wattage I need out of my psu.

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u238

· #11 · Mar 16, 2009

The 4850 can draw about 110 Watts under load, if I recall correctly. So basically add that to the requirement for one card.
To answer one of your original questions: yes, you can still water cool with crossfire. In fact, it is desirable as you can achieve excellent cooling even with minimal clearance between cards. Here is an example:

It's a pretty terrible picture, but you get the idea.

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