EggXpert

My sons system is capable of adding a second card for crossfire.  Here are specs -

Diamond hd3870 video card, Gigabyte GA X38 motherboard, Corsair 750w power supply

Intel E8400 Wolfdale 3.0 GHz processor, 2GB Crucial DDR2 1066 memory, Antec 900 case

The case has a lot of cooling fans and we have an Artic Cooling Freezer 7 Pro CPU cooler.  Thinking about XMAS and saw the HD3870 card on sale for $99.  I recall reading about a lot of heat generated in crossfire configurations. 

If I added a second hd3870 card in my sons system "as is" will I be OK or am I asking for trouble?

Thanks 

It will be fine. and I think your PSU will handle two HD 3870 video cards. it is not a big deal you can change the fan speed and to make them run cool.

Another thing you could look into if you don't mind spending the extra $50 is this video card:

SAPPHIRE Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 CrossFire Supported Video Card

It performs on par with the NVIDIA 9800GTX/+ and performs far better with AA enabled which makes for a much better experience IMO.  A single card setup is nice because you don't have to deal with all of the oddities of software based Crossfire which can vary greatly from game to game and can sometimes have instability issues.  Take a look and give it a thought!

http://www.bit-tech.net/hardware/2008/11/10/winter-2008-graphics-performance-update/1

I need to research how much instabilty/issues the crossfire HD3870 would create..that was the basic question I was asking in this post...heat issues in particular.

Performance wise would a crossfire 3870 combo be better than the standalone 4850 you reference?

Thanks

Any instability is most likely not going to come from heat problems, but instead because of the quality of the drivers you use.  I don't think you will see any problems with heat if you have good airflow set up in the case.

Performance wise, two 3870's can be faster in pure speed, but when you turn on AA and AF the HD 3870s get crushed.  ATI really improved on this when it made the HD 4800 series,  so unless you want high frames with lots of jaggies, I'd say go with the single HD 4850 and get almost the same frames and better image quality.