big performance difference between PCI-E slots?

So I finally got my P5Q Pro back from RMA, the first one was completely unstable but this one seems to be doing fine so far.

Upon first connecting my HD 4850 to the motherboard I got some very strange green artifacts, like a green mesh all across the screen. My first thoughts were "Oh, s*** my card is dying" So I put the card in the other PCI-E slot and same deal. The issue then resolved itself after I reseated the card, maybe the power supply connector wasn't plugged in all the way. It seems to be running fine now so I'm hoping the card's ok.

The artifact issue is probably unrelated to the other problem I'm having but I felt it needed to be said.
The problem I'm having now is that I am seeing a very strange difference in benchmark scores between PCI-E slots. When I put the card in the blue x16 slot, I get a 3DMark 06 score of 11440. If I then change absolutely nothing but the placement of the card in the lower (black) PCI-E slot that runs at x8 bus width, my score suddenly jumps to 12605. Nothing is changed, card is at 650/1050MHz in both slots, CPU clock's the same, etc. Temps appear to be about the same, I haven't really compared load temps but the card idles at 45C with the fan at 65%.

I'm not really trying to break records or get the highest score possible, I'm fine as long as the card runs most games at a high res with decent fps. But this 1200 point difference concerns me since I plan to eventually run another 4850 in crossfire and I don't want to lose performance because of a difference in the slots. Is that a normal fluctuation between PCI-E slots or is there something wrong with my primary x16 slot? This is really confusing and I don't want to have to return this motherboard again.

Here are the two scores that I'm getting (left is x16 and right is x8):

That is wierd.

Maybe the 4850 is too powerful a card and a bottleneck is helping keep your computer in line. lol. hard to imagine that happening but meh.

Sorry, I have no useful information to say. Just a bump in case someone can help and missed this thread.

did u check that he card was running at 16x with say GPUz?

Albyno said:

did u check that he card was running at 16x with say GPUz?

Click to expand...

Yup the slots are read correctly at x16 and x8 PCI-E 2.0

Contact your mobo manufacturer and tell them to suggest ppl to put v-cards to that slot from now on

I would suggest re-flashing the bios and re-installing your video drivers.

Tried flashing the BIOS to the latest release from Asus (1104) and that did nothing. Then I did a clean install of windows and that solved the problem. I guess my drivers setup was corrupted somehow along the way.

Either way here's the new scores at 670/1125 (x8 slot on the left and x16 slot on the right):



All that is left now is to show the card who's boss and max out the overclock

I'm new to this 48xx madness, any recommendation on soft mods and how to squeeze the most out of that card? Would increasing the volts be ok with the stock cooler?