Solved No apparant life!

thigI transferred my Mobo, CPU, RAM and Hard disks to the new Corsair case together with a new PSU and graphics card. Everything else was original and worked before the transfer.

When power is turned on the case and CPU fans run and light up as does the Graphics card. The monitor lights and signals no input. Nothing appears on the screen despite several trys. All conections have been checked and are fine. I can't access the UEFI and no motherboard logo appears. This problem is beyond my limited knowledge so I'm in need of guidence and advice please.

Check you have connected both the large 24-pin cable and the smaller 4-pin cable on the motherboard. Missing the small one it will not boot. Next check you have connected the 6-pin or 8-pin PCIe cable on the graphics card, if it is mid-range or higher. Some high end cards take two cables. Then check your monitor. If it supports multiple inputs you may have to switch to the appropriate input from the controls to get an image. Try connecting your old graphics card and boot. You can also take the computer to the store where you purchased the new parts and let them troubleshoot it for you and upgrade UEFI firmware of the motherboard or graphics card, if necessary.

spapakons said:

smaller 4-pin cable on the motherboard.

Click to expand...

He'll need the 8 pin, normally labeled CPU.

In most cheap power supply units there is only one 4-pin cable. In that case connecting that in the left side of the connector and leaving the right side unconnected should work, but for better stability and performance you need to connect both 4-pin cables combined into a single 8-pin cable. Same if you have an older PSU with 20-pin instead of 24-pin cable. While 20-pin will work, it is best to combine the 20-pin and the 4-pin into 24-pin connector and use that.

ATTENTION: Combining a 6-pin PCIe with an extra 2-pin to create 8-pin IS NOT the same! You have to either use a dedicated 8-pin connector, or combine two 4-pin connectors into an 8-pin or use only one 4-pin connector. Using an 8-pin PCIe (dedicated or 6+2) on the motherboard it will not work and you might damage the motherboard! There are also 4-pin to 8-pin adapters, but not 100% necessary.

PS: From experience when upgrading the motherboard in an AMD system it might not boot because the BIOS (aka UEFI firmware) cannot properly identify the CPU or has some wrong settings. In that case you can reset the BIOS either by shorting the CMOS reset contact for a few seconds or by removing the power and BIOS battery for a few minutes. It should then boot, press the appropriate key (usually DEL) to load UEFI firmware and configure it before first use. Also some AMD motherboards might need a different BIOS version to properly identify newer or older CPUs. In that case you cannot upgrade the BIOS yourself, you have to take the computer to a service and they will put a different CPU and upgrade the BIOS for you.

I suspect that the CPU power connection is not hooked up or is malfunctioning. That connector is very hard to seat properly. Make sure that it is fitting in the connector well.

Pretty sure that board uses an 8+4 for power. Gotta make sure the 8pin is used. 4pin is nice to have but supplemental. Any diagnostic led’s on that board? usually by ram slots

Which Asus Prime 550 is it?

I've only checked the manual for the 550-Plus. It has the QLED set of LEDs that show activity during startup. (Red for the CPU, orange for the RAM, white for the GPU, and green for the OS. In that sequence.)

Do you (BCcanuck) get any of those?

Two separate, 8-pin and 4-pin power connectors are usually present on gamer and server motherboards. A typical motherboard has a single 4-pin power connector and a mid-range motherboard might have a single 8-pin. For that single 8-pin power connector you need a PSU with a dedicated 8-pin cable, the 6+2 PCIe WON'T work and it might damage the motherboard. If your PSU doesn't have a 8-pin or 4+4-pin connector, you can use a single 4-pin cable at the left side, but it won't have the same stability and performance. However, it will work fine.

You might want to go back to basics.

Put the motherboard on the box it came in
Only have the CPU (and cooler), RAM, and GPU in the motherboard.
Only connect the required power for the motherboard and GPU.
Plug the monitor into the GPU.

Boot the computer by jumping the two PWR_SW pins on the motherboard front panel header.
If you can at least test if you can get into the BIOS.

Do you have a PRIME B550-PLUS motherboard? The Asus Prime B550 PLUS motherboards use Q-LED indicators (usually in the top right) to show POST status. If a light stays on, it indicates a failure: CPU (Red), DRAM (Yellow), VGA (White), or BOOT (Yellow-Green).

He should try to reset the BIOS first by shorting the CMOS Reset contacts for a few seconds or remove the battery for a couple of minutes. I have seen it before. The BIOS is corrupt or misconfigured and cannot boot. Once you reset it to default, it works again.

Guys, sorry to have deserted you all in the middle of this problem, an unscheduled visit to the hospital interrupted play. I'm happy to report that both myself and the computer are now just purring along. All of your suggestions were tried as learning opportunities from which I gained both knowledge and experience.