If you're sure that all the connections are correct, and it sounds like you are, then it sounds like you have a v1.6b with Samsung RAM chips. This RAM has different timing than other versions and it causes some BIOSes like Cromwell to FRAG the box as you described.
I had two v1.6b boxes and two SpiderChips to do back in January and had the exact same problem as you. You will need to do this:
- Borrow an UNMODIFIED Xbox that is v1.6 or older (use the versions images on xbox-scene to be sure).
- Prepare a flash CD-RW with EvoX M8 Plus v16 BIOS, use HackDaBox's instructions: http://www.hackdabox.com/Spiderchip_flashing.html
- Install the SpiderChip in this older box.
- Boot the box and Cromwell BIOS should come up. Choose the flash option and insert the disc when prompted and close the tray. If it can read the CD you'll see a progress bar come up and the chip will be flashed. If the controller doesn't work, use an official controller or try re-plugging the controller with the box on the Cromwell BIOS screen.
- If the flash went well, when you restart the box the EvoX logo should come up in the UL corner.
- Great! Now take the chip out and re-install it in your v1.6b.