3870 glitching in new build on vista business. Driver issues?

Have been trying to build a new pc, everything has gone just dandy till it came time to install the graphic card drivers for a Powercolor HD3870. As soon as I installed the ones that came with the card, and rebooted, the desktop had glitchy black lines running horizontally across the screen in small groups. And if i go into device manager, and display it cannot see my card. So I restarted and loaded into safe mode where everything looks alright, and device manager can see a 3870 sitting there, so unistalled the drivers and catalyst. reboot. Then got the newest drivers and ccc from the ati site (8.2) and tried installing them, then on reboot the screen would just go blank once vista started to load. once again, into safe mode, and all seems well, uninstall the drivers and reboot, and vista starts fine. Any help would be muchly appreciated. Keep in mind I don't have another PC that can support PCI-E to test the card itself in, so I would like to rule out all other options before going down the doa card road. Not sure how it works exactly but to me, the fact that I am getting a clean image out of the card before i install any drivers makes me think the card should be ok. but like i said I don't know for sure that graphics cards are like that.
anway if there is anymore information you need from me just let me know.

E8400
Gigabyte X38-DS4
2GB Cruicial ballistix tracer PC8500
Seagate barracuda 160gb
Powercolor HD3870
Vista Business

PS is 600watt, called JSP Bluefire2. Bit of a no namer i realise, i think it is made by pccasegear.com. And I have thought that it could be the issue, but it is designed to run crossfire, and i only have one card in so i kinda figured that it should be able to cope fine. And I have tried taking the card out and re seating it, I'm pretty sure it is all in correctly.

heh, yeah it is plugged into the gpu, also the extra 12v molex on the mobo for the pci-e cards is plugged in. and so the plot thickens. I put the card in the other slot, cleaned ccc and the drivers right out of there, and started with a clean install in the new slot, install goes fine, as soon as i reboot and the windows logo comes up there is lines and random dots of color and whatnot across the screen. SO i go to open ccc, and poof signal drops out then the computer resets, with no signal to the screen. So I reset again, and signal comes back. starts up fine and once again, once the windows logo shows up, there are the lines again. I have also just noticed something during POST and confirmed in the bios. my 3.0GHZ cpu is running at 2.00ghz. Is this leaning more and more toward my cheapskate PSU?

just clarifying, cpu speed has changed recently. couldn't say when excactly. but the first couple of times i booted the machine up and went into the bios, the speed was definately 3.0ghz. didn't really pay attention to it after that, it has just only caught my eye now. anyway, I'm going to go try your suggestions and I'll get back to you.

I had a similar issue when i upgraded to a 3870 from an x1800. Turned out it was a conflict with an addon firewire card. I removed all add-on cards and started adding them back one by one till i found one that caused the issue.

Ok, update. I haven't yet had a chance to take the card anywhere to be tested, thats on the cards for tomorrow. But in the meantime I have: Updated BIOS to F2, updated the chipset drivers to latest version, update .net Framework to 3.5 and tried to install CCC 8.1 instead of 8.2 but to no avail. Still every time it gets past the loading bar window, it dumps to blue screen and reboots. YARGH, damned thing. Can someone confirm for me that the fact that the Display Device and USB 1.1 Host Controller are on the same IRQ channel will or will not cause me these kind of issues.

On a side-note the CPU seems to be running at full speed again.

To wht1986: I don't actually have any other add-on cards in the computer bar the GPU.

To Blacksci: Yeah, tried driver cleaner pro to remove every trace and start from scratch, but I'm still getting the same issues.

Ahh well, tomorrow will hopefully reveal whether my card is fubar'd or not.
I'm starting to hope it is

Yanno, I have actually been thinking just that. Format the drive start again in XP. Its pretty hard to trouble shoot in an OS you know nothing about.