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I use the same machine for development and gaming. I am researching my next PC and noticied the following statement

The PCIEX8 slot shares bandwidth with the PCIEX16 slot. When the PCIEX8 slot is populated, the PCIEX16 slot will operate at up to x8 mode.

Does this mean my gaming PC which is my development PC is slowed down because I have 2 video cards (4 monitors)?

If that is true, what work-arounds are available?

Additional Info

I have a NVida GTX460 (Gaming) and an ATI 3870.

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1 Answer 1

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What I have seen in the past is that your primary PCIE16x will operate normally. However, when you SLI/Crossfire, you will need to set your BIOS up so that it will Run "full more" on the second PCIE16x. For example, If you have two video cards that you will be pairing together and you also have a PCIE Ethernet adapter, then you may find that the ethernet adapter is not recognized in Windows. This is due to the motherboard taking away the bandwidth from the other slots and dedicating it to the secondary PCIE16 slot. I use a very similar configuration 3 Monitors in Eyefinity and 1 Monitor normal. My 4th monitor is actually plugged into the onboard graphics card. I've enabled both PCIE and Onboard to run at the same time. That way, if I am doing something graphic intensive on my Eyefinity setup, whatever is going on, on the 4th monitor doesn't take away from my normal setup. What you're talking about is very typical. I did get tired of my 6770 Crossfire setup and recently switched to 1x 6970. No regrets here.

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thankyou for sharing your experience. I have updated my post to show I am using two cards which cannot be connected. Plus I am after a 4 monitor setup (2 connected to each card) and I could have a 5th montiro if I am able to use the onboard DVI. –  Valamas Oct 15 '11 at 10:16
    
Okay. This sounds similar to what USB does. If you have a USB HDD then you can get a potential 60MB/s. However, if you have two USB HDDs then you still get 60MB/s on each, but they have a shared bandwidth of 60MB/s. So if you're using both devices, the transfer rate of both devices combined is 60MB/s. –  kobaltz Oct 15 '11 at 14:11
    
That is a good explanation. So can I assume that when I am playing a game on one monitor and the monitors on the other card are disabled (not the card, the monitors), that the game I am playing is almost reaching the same speed as if the other card was not in my pc? –  Valamas Oct 15 '11 at 20:56
    
it really depends on how your motherboard spreads out the bandwidth. If your primary PCIE16 is dedicated and not sharing the bandwidth of the other ports then you wouldn't see any difference. Since you're not pairing the cards, I doubt you would notice any performance gains/loss either way. –  kobaltz Oct 15 '11 at 22:44

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