Thanks in advance!
Yes, to answer from prev. thread, I pulled out the dedicated graphics card. MB vid still didn’t work (both VGA and HDMI).
Does the alternate HD need an OS to get far enough for the BIOS to kick in?
Try booting from a bootable CD/DVD or bootable USB Thumb Drive.
Also put some video card in it that has an old fashioned VGA connector. Try a different working monitor.
Try using only one ram stick.
Also use on-board vga if available.

Even if there is no OS, wouldn’t the machine get to the initial BIOS screen?
Or maybe not - I’ve had machines get to BIOS and report a bad HD or missing (cable pulled out), but never tried firing up a machine with a functional HD and no OS.
Is the monitor dead? Try another one. Is it on vga? Digital? HDMI? Try all ports. Try different cables.
The video cables are both fine. I tried them on another computer, same monitors. (VGA and HDMI inputs respectively)
Doesnit beep when you turn it on? Whenever I buy a computer from a thrift store I plug it in and see if it beeps. Also if the num lock indicator on the keyboard flashes briefly. If you don’t have bios output to the display then it is not any use to try to figure out which boot device you should use. It has to get far enough to boot.
I am FAR from a computer expert, which on your previous post I said Geek Squad. I pay a yearly fee and they always solve any computer problem. It has saved me money. The time to solve a problem can get expensive. You may know much more than me, but let others solve problems and pay.
A lower end mobo might emit coded beeps to a traditional PC speaker connected to a pair of pins on the mobo. Again the beep codes will vary.
No beep, no LED display. Has a button for apparently some sort of memory test - looks like it maybe parallels tiny button labelled for same on MB. It does "something" - the fans change speed when either is pressed, and a red LED comes on briefly.
Can't ask brother about anything, he is dead. (last Jan. - like I said, I inherited this baby.) Case says NZXT. It is probable my brother built this thing - he definitely had the knowledge to do so. But he had severe COPD and likely got so bad toward the end that if something went wrong, he didn't have the energy to do much about it.
Motherboard is ASUS, M4A89GTD PRO/USB3. 850 watt PSU, Radeon HD5870 Graphics card - the biggest graphics card I've ever seen! (Full length, double height.)
MB has outputs for a full 7.1 Dolby Surround system - could be very nice! :-)
A capacitor in the power supply may be blown. Try swapping out the power supply. You could take the power supply apart and do a visual inspection. If you see a bulging capacitor or two, that might be your problem right there.
Can you swap the power supply?
Check all connections.
Based on not seeing the bios post then you have a hardware failure. You don’t even need a hard drive to get the bios screen. You do need a good motherboard, power supply, CPU, and Ram. You could try unplugging all drives in case one has a short or the power supply is weak, but that is unlikely.
Is the monitor used for gaming (and any other required unit, like the laptop you mentioned) properly connected to the correct A/V ports and turned on?
Did you ever see your brother use the game system you inherited? Are you doing what he did to get it all going?
Is there any documentation that came with the game system that explains how it should be set up?
Do you know anyone that gamed with your brother on the game system? Can you reach out to them to see if one of them can assist you? Maybe they can help you find the online forums for your brother’s favorite games and someone out there can help you.
Does the entire system from one specialized gaming outfitter? If so, contact them about your case. There may be user a forum or a tech that can help you.
There are professionals that put together gaming systems for clients. You might track down someone in your locale that does that and see if they can diagnose, trouble-shoot, or set up yours. Look at professionals that put together home entertainment systems, too. They may be able to handle it or put you in contact with someone who can.
Good luck!
Your mobo is socket AM3, e.g., the AMD Phenom II (circa 2010). Phenom II was one of the fastest CPUs of the era, but today it is hopelessly out of date.
The repair cost plus your time and effort would likely exceed the replacement cost with a modern low end PC with a low tier NVIDIA GPU.
I had that problem once. Turns out I bought the wrong memory for it. But since you inherited the machine, try seating the memory it has. Also research the motherboard and memory and ensure they are compatible.
Paul -
Just saw your post, let me offer you some free help from thirty years of providing support. Lots of good info in the replies and information.
What you describing is known as a POST (Power On Self Test) failure.
So properly diagnose the specific problem, start by unplugging power then disconnect everything from the motherboard that isn’t necessary for booting. That includes the hard drive(s), Optical (CD/DVD) drives, any USB devices (except the keyboard), including the mouse (it’s not needed for booting), any daughter cards (graphics, audio, whatever is installed the expansion slot), case fans, etc. Disconnect case fans, but keep the CPU fan connected. Remove all but one memory module (preferably in the first slot), check to see if you have a motherboard speaker and connect just the vga video cable.
Before you plug power back in, unplug and replug the power supply connectors into the motherboard. Check that the vga and keyboard are connected and the monitor is turned on.
Power on the computer. Check that CPU fan is turning. Watch to see if the monitor power LED changes color (typically from amber to green or blue). Listen for any beeps from the motherboard speaker (if available). Watch ANYTHING to displays on the monitor. If you see anything at all, start tapping either the DEL or F1 key and see if you can get into the BIOS.
You can personal reply to me with the test results and I’ll be happy to go even deeper if you’re interested.
If the power supply checks, I would go with post #50.
Needs proper and good ram to get the beep
Use the spkr out to a small spkr if it is not in a case
hope you get it
What happened the first time?