Question iMac G5 A1058 displaying gray screen on bootup?

[ragnarok0274]

Some of you may remember my iMac G5.
Now it has Mac OS X 10.4.6, from an official Apple disc.
So calm down, moderators.

Unfortunately, the next day after installing the hard drive died. I heard a soft grinding noise and then partway through the white screen with the Apple logo and the spinning gray circle I hear "vrrrrRRRRRR-SCREEEEEEECH" and then it stops booting and shuts off.
I then remove the hard drive and set it aside to take apart for fun.
I had a Samsung 850 EVO 250GB 2.5" SATA III SSD + 2.5" to 3.5" drive bay adapter laying around, so I put that in after formatting it to Apple Partition Table & Mac OS X Extended (Journaled). The SATA cable wasn't long enough, so I swapped that out and shoved the extra under the drive.
I booted from my disc, installed it, and rebooted the system. I got a blank light blue screen, but that happened with my hard drive, so I didn't think much of it.
I restart it again. This time, I get a blank light blue screen again, but only for about half a second. Then the screen turns gray.
I go to Google and it suggests booting into Safe Mode. I do so, it boots up fine, and I set my iMac up. After it was set up, I rebooted the system without Safe Mode and it gave a gray screen again.
Apparently PowerPC Macs don't like SATA 3 drives and/or SSDs in general, but the fact that it installed and booted in Safe Mode makes it kind of unlikely.
Don't know though, I'm not an expert in PowerPC. This one stopped working when I was 7 (it was my grandparents and I used it from 4 onwards until it broke, which is why I'm not getting another)
Any advice?

No, I'm not paying someone to fix the drive.

 

[RamBoy_69]

One of the most common problems that can cause the gray screen issue is a bad peripheral or peripheral cable. When a bad peripheral is plugged into your Mac, it can prevent it from continuing the startup sequence, and cause it to stall while it waits for the peripheral to respond to a command. The most common form of this is when a bad peripheral or its cable causes one of the signaling pins on one of Mac's ports to get stuck in one condition (set high, set low, or shorted out to ground or positive voltage). Any of these conditions can cause your Mac to freeze during the startup process. If your Mac starts back up without issue, then you'll know that it's a problem with a peripheral. You'll need to shut your Mac back down, reconnect one peripheral, and then restart your Mac. Continue this process of reconnecting one peripheral at a time and then restarting your Mac until you find the bad peripheral.

 

[ragnarok0274]

One of the most common problems that can cause the gray screen issue is a bad peripheral or peripheral cable. When a bad peripheral is plugged into your Mac, it can prevent it from continuing the startup sequence, and cause it to stall while it waits for the peripheral to respond to a command. The most common form of this is when a bad peripheral or its cable causes one of the signaling pins on one of Mac's ports to get stuck in one condition (set high, set low, or shorted out to ground or positive voltage). Any of these conditions can cause your Mac to freeze during the startup process. If your Mac starts back up without issue, then you'll know that it's a problem with a peripheral. You'll need to shut your Mac back down, reconnect one peripheral, and then restart your Mac. Continue this process of reconnecting one peripheral at a time and then restarting your Mac until you find the bad peripheral.

Two things:

1. You took that directly from this website. If you're going to quote something, give proper sources. Otherwise it's plagiarism.
2. I did exactly that already. Apparently I didn't mention it here, probably on the Linus Tech Tips forum.