Ok so I have 2x 6870 ATI cards both made by XFX. I ran the 3D mark and scored a P6387. Most poeple were scoring in the 7k to 8ks for my same setup. I look in my computer Performance and information panel to see that my Graphics are scoring a 6.0... WTF? I used to have an OLD GTX 280 that was scoring MUCH better than that. I don't put too much stock in that, but with the Bench marks low, and this showing up I'm wondering what could be messing up my system.
CPU: Intel Core i7 920 LGA1366
VIDEO: x2 AMD ATI 6870 1GB cards(made by XFX)
RAM: Corsair Triple channel 2BG x3 kit(1600) 6GB total
MOBO: EVGA X58
HD: Crucial 128GB SSD
OS: Windows 7 64
One of my possible concerns was with the PSU.... its a 900watt Antec that is "designed for crossfire/sli" Here is my concern, I did check how much power was on each rail before hooking my cards up, but there is only 2 ports on my modular unit that power the video cards. So I am running 1 from each output a direct cable to each card, but each one is split per 2 inputs per card. The manual says run 2 cables per card, but I have read as long as your psu doesn't split the rails in such a way that you won't get enough wattage out of each cable you should be fine. Even so, I'm still worried that I could be starving my cards of power. Its the only thing I can think of. Any help or thoughts would be greatly appreciated.
you def need to make sure your cards are getting 2x4 power pins failing to do so could blow them. If your power supply is cf/sli ready it should have the necessary power outputs for 4x4 pins 900 watts is perfect in my opinion 300x2+140 CPU 800 watts full load for system.
So if you look at the plug options on the images in the link, you see there are only 2 6pin pci-e connectors(red ones), I was WAS(I installed a single card for now), running 1 cable from each of those connectors that had a "y" in it for each card. Are you saying I should find a cable that goes from one of the 4pin ports to the 6pin on the card??? With 1 card in my windows video card score actually went up by .4 to 6.4 from 6.0. My single card 3D mark11 score was right in line with what other people were running.
I would recommend a new power supply if you want to Crossfire. The problem is that a lot of the power on that PSU is on the +5V and 3.3V rails, which doesn't do you any good for your video cards. It's probably at best just barely adequate for a 6870 Crossfire. Coolmax has a really bad reputation for their power supplies.
Each 6870 has 2 6 pin connectors, you have 2 6 pin, and 2 8 pin PCI-E. Unless your 8 pin connectors are actually 6+2 pin, you're going to have to get adapters to try and power your second card with that PSU. If you get the adapters, your Crossfire setup may work properly, though I wouldn't trust any Coolmax PSU with that much juice.
Yeah, with my 280 GTX I had a 7.8 also. I don't recall what it was with the 6870 before I installed the second card. As for what Supernova11 said, yeah I was looking at tear downs of my exact power supply and tests at load etc. What I found was the my 950w is barely a decent 700w, and that it spikes all over the place. The "silver rating" also is pretty much false. So I looked up Gold to platnum rated PSU's with 6x 8 pin pci connectors. I found that this one:
I use a single XFX 6870 and my graphics score went as high as 7.8
Just to do some testing, I pulled out one card, re-ran my windows experience index. As you may have read I got a 6.4. Then just recently I pulled that card out and put my other card in. Strange thing happened.... it said there was no driver installed. So I installed the driver for what I thought was the exact same card and ran the windows experience index, boom... 7.8. Does this mean something is wrong with my other card or the drivers were messed up? I'm going to re-install it again, but before I do I'm going to run the same bench mark I did with the old card and compare the scores.
So, even if the other card is still scoring 6.4 does that really mean something is up? I mean... how reliable is WEI anyway. It does have me concerned as it may be a warning some how about a problem with the card. I have noticed a slight flicker here and there on my secondary monitor(maybe once every 3-4 hours, almost like a resolution change). Anyway... ANY thoughts comments, or ideas about how I should move forward. I will have a better PSU/case/cooling for the entire system in a couple days... but I'm thinking I should see about a RMA from ATI on the current card. Its about 10 months old now. Think that's a good idea?