Computer won't boot with graphics card installed

Klorgnum

EDIT: Earlier problem solved. Now, the computer won't boot if I have the graphics card installed. Everything is fine if I use onboard video, but using the graphics card results in a blank screen and no hard drive activity past the initial bios splash screen. Anyone have any ideas? I can't even get into bios setup.
I'm sure I installed the card correctly, and made sure it was seated right.

Computer info:
Gigabyte GA-MA790GP-UD4H motherboard
Powercolour Radeon 4650 512MB DDR2
2Gigs DDR2 ram
Athlon II x2 3.0GHz



I've just built my first computer, but I'm having trouble installing Windows 7 (The motherboard only beeps once when I start it up, and according to the manual, that means everything's fine, so I don't think it's a hardware problem).
Every time I try to boot from the DVD, I get an error. Either I'm stuck with a black screen and a useless cursor, or a message saying "File is possibly corrupt. File header checksum does not match computed checksum." or I just get a vertical column of the letter "D". It's a legitimate copy of Windows 7 OEM as far as I know (bought it myself). Never been used. The only thing I can think of is that I haven't formatted the only hard drive in the computer, I've just deleted the partitions on it so that it's all unpartitioned space.

I'm going to try to format it properly now, but I don't have high hopes. Has anyone encountered anything like this before?

Buttcleft

formating the harddrive isnt going to do jack if the system cant read the cd.

first suggestion, make sure your IDE/SATA cable for your CD/DVD drive are inserted fully.

second suggestion, check with a second optical drive if you have one handy.

Klorgnum

I couldn't find anything wrong with the IDE connection, but I decided to try removing the graphics card and switching to onboard graphics. It seems to be working now.

Hopefully this doesn't mean I've got a bad graphics card...

EDIT: Aaaand now the install seems to be frozen. It's just displaying some fancy wallpaper.

EDIT2: Ejecting and reinserting the disk fixed it.

Lemming

Does it require additional power? Some cards require you put in another power connector in the side, like a six or eight pin one that comes from your power supply.

Klorgnum

Not as far as I can tell. There don't seem to be any power sockets on it.

Klorgnum

Tried a new graphics card (Sapphire Radeon 5670 512MB), exact same results, so I guess it's got something to do with the motherboard. Power supply should be fine - 430W Antec Basiq.

EDIT: Just upped the power supply to a 700W Powercooler