S.O.S I don't know what to look at anymore…

[boncoe]

Hello everyone, it turns out that I have built a secondary computer consisting of a Tacens Mars Gaming case (new), Tacens Mars Gaming 600W active power supply (new), Gigabyte 650 GTX OC 5gb graphics card (new), 1x2gb DDR2 800Mgh Kingston RAM (used), 1x2gb DDR2 800Mgh Corsair RAM (new), two hard drives (used), a writer reader (used), a card reader module (used), an Intel Q8200 2.3 Gh processor (used), and most importantly, a Gigabyte P5KPL-CM motherboard (used).
The thing is that in the previous computer, the used parts worked perfectly. I assembled the new computer with the new and used parts and when I tried to turn it on, everything worked: the motherboard fans, the hard drive made noise and seemed to be running, the writer reader, the graphics card, etc., but the monitor stayed on standby and didn't receive any image.
I've already checked everything, cleaned the RAM slots including the RAM with a rubber, removed the heatsink and applied new Artic Silver Ceramique 2 thermal paste, the motherboard has an integrated graphics card so I removed the dedicated graphics card and put it directly on the motherboard and it did the same thing, I tried with one RAM slot, with two, changing their positions, etc.
The tower has a connection that is a speaker that connects to the motherboard via a 4-pin connector, I imagine it's to alert you of possible acoustic failures, but the motherboard doesn't make any sound even when booting without RAM.
Please, I've been working on this for two days and there's no way, can someone guide me or tell me what could be wrong??,
Thanks

[Fassou]

Try with the old source, and if you have managed to remove the micro from the socket, check the pins.

Salu2!

[ferelxyx]

try using a single memory, as they are from different brands. regards

[boncoe]

Thanks for your contributions, but I have already solved it. The issue was that I had forgotten to connect another power cable to the board and there was no way to see it, it was already saturated with so many cables of colored connections etc.
Best regards

[Fassou]