Ok here is my situation. I just put together a PC for my nephew prerebuild was a PentD 3.2 (yea I know), 4 gig mem, Saph 1650 pro DDR3 GPU, xp pro 64bit, screen resolution 1680X1050 22" LCD.

BF2142 ran great, BF2 ran great, EQ2 ran great, so on.

Placed in a Diamond HD3850 256, uninstalled drivers, ran driver cleaner installed 7.11 7.12 and tried 8.1. Going down to even 1024X780 was horrible.

Now every game is lagtastic and shutters. When I did my HD3850's mine were brought in a duo core system. I could see the difference. In his it got worse.

I ran 3dmark 6 pre GPU upgrade gave me a CPU score of 2035 post upgrade a score of 500.

Just want to make sure of this before I make him mow my lawn for the summer for a new MB and CPU.

Forget about bottleneck something else is not working correct. Bottlenecks means maybe losing 5-10fps not just not working. Sounds like the card isn't throttling out of power saving low clocks. Bottleneck is at low rez not the rez you have there.

Yeah, there's something not working right there. Probably a driver conflict of some sort. Try uninstalling/reinstalling the drivers (again) and see if that does anything.

Worst case scenario, you may have to just nuke windows. I know, it's a pain, but it is the fastest and most effective way to solve any driver conflicts, as well as get rid of any crapware that may be on the system.

Yea thats the last resort I will have to do.

Gonna still make him mow my lawn if I have to do that.

What kind of PSU do you have?

How is the case cooling, do you have enough fans in there?

AHA! That very much could be the issue. The difference in power draw between the two cards could be very significant. Could be that you're overloading your (presumably) older power supply and it's not giving it enough juice. While it's not as bad as the 2k series ATI cards, that card is still rated at drawing right around 100 watts by itself.

Knowing some pertinent information about your PSU could help expedite this discussion.

Brand new crossfire approved (ATI site) Thermaltake ToughPower (W0103RE) (600W).

cooling is not an issue.

That PSU should be plenty.

Can you try with one of your HD 3850 cards instead? If that works you just need to RMA the nephew's card.

prolly a bad card? did you check for hardware conflicts? or pop the card in a different system? also try a 32 bit OS i know that i had xp 64 and i couldn't get crap to run on it... annoying as hell...

I could get about 2/3 of my "crap" to run on xp 64.
Yeah, you have a better chance on xp 32.

UPdate

BAD MB! MB wouldnt even take a bios update.

Took one of my 3850's over thier and plopped it in. Same crap lag and score.

Took my spare d97xbx2 installed it lag was gone and had a better score. Still a low score in CPU in 3dmark6. My brother went out and bought a new processor 2.13 duo core. LAG is completly gone and now has a 3dmark 6 score of 10023 under vista 64 ultimate.

So my nephew only has to mow my lawn half the summer now.

Thats good. I've been there myself. I was convinced it was a bad card so RMA'd got another same problem. Used an old tried and tested card to find the problem was the mobo. In fact I can't believe I didn't think of that seeing as I was using 3d mark as a test aswell (only thing its good for).

they prolly had updates for x64 xp since i used it. i just know that it was a headache any time i wanted to use something, and half the time i'd just have to wait for drivers and what not.

glad to hear you got it all worked out. half the summer at one mow/week is only 6 mows... at what the parts cost... i'll mow your lawn in trade? haha :-p