Computer POST Beeps after changing DVD Drive

Hello everyone, I am experiencing a problem far too unique to even attempt googling this.
I have a PC from around the early to mid 2000s that I've started messing around with, and I changed this CD-Rom drive with a DVD drive.
Once i closed everything back up and booted up the system...I got a beep code, 1 long, 8 short. I googled this, and it appears to be a video card error. The hard drive spins up, I can hear the speakers for a second, ethernet lights and activity lights are on, but no fan activity at all.
Confused, I decided to reseat everything in case I knocked a cable loose, and as soon as I flicked the PSU switch on, it booted up, Windows XP loaded, and I was able to confirm that my DVD drive does work. After I turned it off though, put the side panel back on, it just throws the same error. I tried reseating everything again, but no luck.
I have an AGP Card (ATI 9800 Pro) and I know those usually don't have a very long lifespan. But I wouldn't imagine it dying like this, after simply changing a DVD drive. Especially since I saw it work fine for that one moment.
Any help would be greatly appreciated.
Specs:
MSI 865PE Neo2-v
1 GB DDR Ram
P4 2.8 GHz
ATI Radeon 9800 Pro (as previously mentioned)
80 GB HDD (sata)
IDE DVD-ROM drive

phillpower2 said:

What actually happens now as in any No Signal message on the screen and are you still getting the same beep pattern

Have you tried disconnecting the new drive and hooking the PC up to a different screen.

What is the brand and model name or number of the PSU and how old is it.

Have you tried pulling the CMOS battery and putting it back in after a while.

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There is no signal going to the monitor, and I don't think there would be any because it POST Beeps instead. I did try disconnecting the drive, tried using the old one, but still nothing, which made me think i knocked something loose in the PC.
The PSU is very new, I don't mess around with older units, I don't want a fire hazard in my house. It is a Corsair CV550.
I don't think the CMOS would have anything to do with it, as it's worked fine the same day I performed this upgrade.
However, today, I turned the PC on and it seems to work OK. If there is any further problems, I'll try the stuff mentioned above.
Thank you for your help.

Bruce said:

Not the first time you get a win like this, and won't be the last.

Click to expand...

No win like this today for me sadly... After about a minute of running, all of the fans just stop, video goes blank, but PC stays on and i need to power it off manually. The PC then throws the same beeps once i try turning it back on, and it needs to cool off for about 20 minutes before it can boot again. I'm thinking it could be a PSU issue that the BIOS points to the GPU for some reason.
Any thoughts?
Again, any help is greatly appreciated.