Help Choosing Gpu - Overclock.net

gunzkevin1 · 08-27-09

Hey guys. As you can see my computer has some aging components I guess. So I was thinking of adding a 2nd gpu to the equation. Maybe a 4870 as this one http://www.newegg.com/Product/Produc...82E16814131140
with a good looking cooler for $127, rather than another 4850 for like 30 bucks less like this one http://www.newegg.com/Product/Produc...82E16814102824 I think the performance of crossfiring a 4850 with a 4870 rather than 2 4850's would be worth the extra 30ish bucks. Am I correct? And would my psu be able to support these?
http://techreport.com/articles.x/16229/13
in that it shows that 2 4870's which would require more power than 1 and a 4850 requiring under 500 watts. And that is the whole system and the system they are using an i7 and 6 gigs of ddr3 ram. Much more than my system would draw I assume. So my psu should be fine right? It was a snag for 30 bucks with something else I bought. here she is
http://www.newegg.com/Product/Produc...82E16817182032

And can someone tell me how you guys put a link but have it say here and you just click on here and it will go to it. Or any other writing as the link. Haven't figured that out yet.

**metallicamaster3** · 08-27-09

The 4870 would be downscaled to match with the 4850 during Crossfire so you might just want to get the two 4850s. I would get two 4870s if you could spare it -- and your motherboard should definitely be able to handle it. How much amps are on your 12v rails? You should have at least 38-40 for crossfiring two 4850s or 4870s.

gunzkevin1 · 08-27-09

Quote:

Originally Posted by metallicamaster3

The 4870 would be downscaled to match with the 4850 during Crossfire so you might just want to get the two 4850s. I would get two 4870s if you could spare it -- and your motherboard should definitely be able to handle it. How much amps are on your 12v rails? You should have at least 38-40 for crossfiring two 4850s or 4870s.

Ummm I believe 19a? Here are the specs
Output l +3.3@30A,+5V@55A,+12V1@19A,+12V2@19A,-12V@1A,+5V SB@2.5A

Are you sure that's what happens when you crossfire 2 diffrent chips? They just make them equal speed? Can you prove this cus I don't believe this.

**metallicamaster3** · 08-27-09

You have two rails at 19A each. Hmm, it'd be cutting it a tad close but you shouldn't have any problems with the quality from Rosewill.

Blameless · 08-27-09

Quote:

Originally Posted by metallicamaster3

The 4870 would be downscaled to match with the 4850 during Crossfire so you might just want to get the two 4850s.

I was under the impression that ATI's drivers would simply balance the load to get the most out of the two cards.

gunzkevin1 · 08-27-09

Quote:

Originally Posted by metallicamaster3

You have two rails at 19A each. Hmm, it'd be cutting it a tad close but you shouldn't have any problems with the quality from Rosewill.

Ok, can you answer the other question in my post too.

**metallicamaster3** · 08-27-09

From ATi's FAQ:

Quote:

5. What happens when graphics cards with varying memory speeds and engine clocks are paired together?

A. In this scenario, overall performance will be adjusted to match the memory speeds and engine clocks of the lower clocked card. To obtain ideal performance, graphics cards should be paired correctly.

http://ati.amd.com/technology/crossfire/faq.html

esocid · 08-27-09

You can't force it to perform out of its technical range. They'll both run at the highest clock that the lower card can run.

Get a 2nd 4850 unless you plan on getting another one to match whichever better card you decide on in the future.

gunzkevin1 · 08-27-09

Quote:

Originally Posted by metallicamaster3

From ATi's FAQ:

http://ati.amd.com/technology/crossfire/faq.html

You win this round.

**metallicamaster3** · 08-27-09

Well yeah, If you were to overclock the less-clocked card to match the higher-end one, then yes, you'd run at the ideal range for both cards of the higher end one.

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Help Choosing Gpu

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