I have been lurking and occasionally posting over at dfi-street since I first built my DFI rig back in July of 05. By reading about other people's problems (and troubleshooting quite a few of my own), I went from a totally noob to where now I can handle pretty much anything my computers can...
I guess everybody's experiences are different. It's also dependent on the specific capability of the individual components. I've been running the Rebels Haven mod of the CU51M811 bios and I lucked out on my opty 144. Not prime stable at 3150GHz up to 1.55v, but is prime stable at 3000GHz at 1.4v.
They seems to do just fine for a smaller outfit. I placed my order on 7/3, but they were closed for the 4th of July holiday. I had requested a different shipping address than my billing address which only delayed things for one day, but once the credit card issue was cleared, the chip shipped...
Biostar makes one with AGP (XGP) and PCI-E
http://www.newegg.com/Product/Product.asp?Item=N82E16813138248
note: the "XGP" slot is not compatable with all AGP cards though.