I have a board with 3 PCI-E slots. 1 is X16, the other two are X8. Are there any issues with the X8 slots (bottleneck)? From what I have read, when using the X8 slot, this will slow down the X16 slot. Is this correct? Seems cheaper to crunch with GPU's than CPU's. Kind of considering this move since more projects are turning toward GPU crunching. Any help appreciated.

I have a board with 3 PCI-E slots. 1 is X16, the other two are X8. Are there any issues with the X8 slots (bottleneck)? From what I have read, when using the X8 slot, this will slow down the X16 slot. Is this correct? Seems cheaper to crunch with GPU's than CPU's. Kind of considering this move since more projects are turning toward GPU crunching. Any help appreciated.

No it is not a problem, the gpu does not transfer that much data thru the pci-e slot when crunching. Of course the data going on and off the gpu will be faster in an X16 slot but once on the card it stays there until it is done and then gets rid of the one unit and gets another one. It is not like a video game constantly showing something as it goes along.

There are couple of things you will need to do though, you need to hook up a monitor to each gpu on bootup OR use a "dummy plug" to simulate a monitor. You can see how to make your own "dummy plug" here:
http://www.overclock.net/t/384733/the-30-second-dummy-plug

You hook one monitor up normally and then every other gpu gets a "dummy plug" instead of a monitor. You also need to SOMETIMES load the gpu software once for EACH gpu, sometimes you do and sometimes you don't. You will have to see what works for you. What works for me is to get one gpu up and running, then shut the machine down and install the 2nd gpu. During the startup process Windows will find it and load the software etc and then it will say it need to reboot, or sometimes it doesn't say that. I ALWAYS reboot, then I go into Boinc and look in the Event log and see if it found both gpu's or not. You will ALSO need to put a cc_config.xml file in the Boinc directory telling Boinc to use all the gpu's it finds, this depends on the project you are crunching for though.

Thanks for the help.