I have a HD-587A-ZNF9 XFX 5870 1GB card and recently purchased another XFX 5870 1 GB card HD-587X-ZNFC. The cards are slightly different in physical dimensions. The new card is slightly shorter and has power connections at the rear of the card instead of the top like the old card. The ZNF9 has a fan towards the rear and the ZNFC has the fan in the middle. The ZNF9 is installed in the slot immediately above the ZNFC.
I installed the ZNFC card into the second 16x PCI-E slot on my EVGA FTW3 motherboard (i7-950 processor). The two slots are next to each other in the middle of the mother board. The new card's PCB is extremely close to touching the fan of the old card.
The old card does not look like it can pull in air from the fan side of the card. The old card is running 30 C hotter with the 2nd card installed (90 C max under load) with the fan running in the 75-90% range. The new card is running around 60 C - 65 C.
I stopped gaming when I saw these temperatures (Dragon Age II - all settings maxed).
I have a Coolermaster 690 case with 2 x 120 mm front inlet fans, 2 x 120 mm top exhaust fans, and 1 x 120 mm back exhaust fan. The fans are medium speed. The power supply draws in case air and exhaust out of the case.
Are these cards designed to be installed "back to face" in a crossfire configuration? What are the temperature limits of the cards?
I can install one of the cards in a lower PCI-E 8x slot if I have to, but I'm going to need a longer Crossfire bridge and will have to drop down from 16x to 8x.
I switched the card positions and installed a 140mm fan blowing right on top of both cards. The upper card temperature is maxing out at 84 C, but now I'm getting some graphical stutter and artifacts. I hope the high temps didn't fry one of the cards.
The noise is unbearable, so I'm going to install one of the cards in a further away 8x PCIE slot.