Crossfire Question

[Trueno07]

I have recently built a new system with a radeon 5850, and i have a question about cross fire.

First off, both my motherboard and power supply support it, so no worries there.
( Corsair 650w, Gigabyte GA-890XA-UD3)

Here's my question:

Let's pretend i didn't want to spend another 300$ for a performance increase. Could i crossfire this 5850 with a 5770 or 5830 and get a good boost, or would it drop my 5850 down to the level of the weaker card?

Also, i hit "Auto-Tune" in ATI Catalyst menu, and my screen went black, and came back with all these green-ish/yellow-ish lines running vertically and horizontally. I reset, and everything is fine, but is that normal? Also, my clock speeds are at 400MHZ GPU and 1000MHZ Memory clock. Is that default for an XFX Radeon 5850 (The full sleeve one), or did it change something? Dumb question, i know, but i forgot to remember the stock speeds.

 

[jefe323]

I have recently built a new system with a radeon 5850, and i have a question about cross fire.

First off, both my motherboard and power supply support it, so no worries there.
( Corsair 650w, Gigabyte GA-890XA-UD3)

Here's my question:

Let's pretend i didn't want to spend another 300$ for a performance increase. Could i crossfire this 5850 with a 5770 or 5830 and get a good boost, or would it drop my 5850 down to the level of the weaker card?

Also, i hit "Auto-Tune" in ATI Catalyst menu, and my screen went black, and came back with all these green-ish/yellow-ish lines running vertically and horizontally. I reset, and everything is fine, but is that normal? Also, my clock speeds are at 400MHZ GPU and 1000MHZ Memory clock. Is that default for an XFX Radeon 5850 (The full sleeve one), or did it change something? Dumb question, i know, but i forgot to remember the stock speeds.

you cant crossfire a 5850 with a 5770 (http://game.amd.com/us-en/content/images/crossfirex/CF_combo_chart.jpg)

you can crossfire a 5850 and a 5830, but i believe the 5850 will be downclocked to match the 5830. You can overclock the 5830 to match the 5850 however.

I would recommend getting 2 5850 to crossfire

 

[wolfram23]

I wouldn't exactly say it will downclock to a 5830 level. It's hard to say, definitely not recommended but it could work out for you. I know that I can OC my CF 5850s to different clocks and get a performance boost. I did it by accident by OCing only one card and running FurMark, then realised the mistake, OCed the 2nd card and reran the test. Showed improvements both times (obviously a greater improvement with both OCed).
I'd really recommend saving up to get a second 5850 tho.

As for the Auto-Tuning... yes that's normal. And don't do it, it takes forever. Just set them to the max CCC setting if you want to make it easy. Really tho, download MSI Afterburner and use that. You have to change a line in the config file "allow unofficia overclock =" from 0 to 1. Then you should be safe to get at least 850 core, 1150 memory. Or higher. I can get 875 core on both my cards, but one of my cards is limited to 1190 mem while the other seems ok at 1210. I've OCed the cores higher with more voltage, but I have both mem clocks set to 1190 for simplicity.

 

[Trueno07]

Best answer selected by Trueno07.