Face issues with PSU cable upgrade—black screen and VGA LED lighting.
Face issues with PSU cable upgrade—black screen and VGA LED lighting.
Hello everyone, I recently changed my PSU cables to a CableMod compatible set. I made sure each connection was firmly placed, but when I tried to boot up my system after the switch, I saw a black screen and the motherboard’s VGA LED stayed red. I’ve double-checked all the connections, yet the problem continues. I’m not sure what to do next and would appreciate your advice to help fix this. Here’s what I’ve already attempted:
- Rechecking all cable connections: confirmed everything is plugged in correctly and positioned.
- GPU placement: verified it’s seated properly.
- Testing different display outputs: checked both the graphics card and motherboard video ports, but the screen remains black.
My system specs are: 7800X3D, 32GB DDR5, 6000MT/s, CL36 RTX 4090 Aorus B650 Elite, Aorus C1300, and I’m using a CableMod C-Series Pro ModMesh Sleeved 12VHPWR cable.
Thank you for taking the time to read this and respond. I hope we can resolve this soon.
Sorry to hear about the issue with the cables. It sounds like the angle adapter may have been defective as well.
12VHPWR performs well in detecting power when fully seated. I’d notify Cablemod about the situation. I’d make sure to test the cable under load, as it would otherwise reset and shut down after a short heavy GPU session. I ended up getting a replacement cable and a dedicated 12VHPWR PSU. If you reach out to support, double-check for any further problems. For testing, I simply played in the Plains map in Warframe—it took a few minutes before it crashed completely. I’m not worried about the card unless you notice visible damage; I’ve used and stressed my RTX 4090 with several PSUs, including a Thermaltake GF3 1600W, which still works fine.
The RTX 4090 offers remarkably consistent power usage, unlike the RTX 3000 line which can jump to 1.5 to 2 times its TDP. My lab has verified this. I’m using a 1200W unit because I wasn’t certain whether Intel would be the right choice. This site provides reliable advice—ASUS Power Supply Units | Republic of Gamers | ASUS United States. The overclocking switch affects the CPU, unlike the 7800x3D which is more limited. In practice, a 65W processor can reach up to 120W, making it similar to older generations rather than the newer i5/7/9 models. Before switching to a 1200W, I ran an RM1000x with the same overclock and had no problems. Based on my experience, 1000W should suffice. If you’re planning to overclock a 13th gen i7 or i9, go with 1200W, but avoid the 7800x3D.
1000W provides enough power, not too much extra. Running off a 750W unit would still work but isn't ideal. At least 850W is needed for an RTX 4090, though 1000W is usually recommended for most AIBs. This setup sits perfectly at 1000W, giving you room to expand later if desired. I chose 1200W because it was available for about $30 more.