Dell Optiplex 390 not turning on with power button

[joshchron1]

So I'm fairly new to the PC world, i Finished my first completed build just yesterday actually. I know a lot about putting them together, but this stumped me. Whenever I pushed the power button this morning nothing happened. I've tried to troubleshoot the best that i could, but i don't know whats happening. Yesterday I installed a Corsair cx450m and a Geforce gtx 750ti, the motherboard still has power so I don't think thats the issue, and i took out my 750ti and it still didn't work, if anyone could help me out that would be appreciated.

 

[william p]

Check your old PSU for the Wattage on the 5V. rail and compare it to the Corsair. Some older Dells stayed with a high 5V. usage on the MB. Try putting the Dell PSU back in. You don't need anything more for a GTX750Ti anyway. It can run off of the PCIe slot unless you got an oddball card with a 6 pin PCIe socket.
If that's not it. Are there any colred LEDs on the front of the case lighting up? Either in the power button, or above it by the USB slots? These are Dell diagnostic codes listed in the manual.
http://www.dell.com/support/home/us/en/04/product-support/product/optiplex-390/manuals

 

[King_V]

A few suggestions from the "so obvious that they're easy to miss" department:
- Maybe any connectors that could have come loose? Including the small one from the power switch?
- Possibly the on-off switch on the back of the PSU?
- Possibly the wrong switch position on the 120/240V switch on the back of the PSU?

 

[joshchron1]

So update:
Whenever i turn the switch on the back of the PSU it turns on for half a second then powers down. Does this mean anything? Also my card does have a 6 pin that needs to be plugged in or else it wont work. Also what do you mean by the 120v to 240 volt?

 

[william p]

EVGA PSUs have the needed 5V. power on most models. If you don't have enough power from the PSU it will fail the Power ON Self Test (POST) and shut down.
Older PSUs had a 240 V. switch position for European markets. Newer ones auto detect this.

 

[william p]

Here's another possibility. Did you remove the old GPU drivers in Safe Mode before installing the new GPU and drivers in Safe Mode (F8)? The computer might be running OK but no display due to incompatible drivers..
Those are 2 very common problems with Dell PSU, and GPU upgrades.
Monitor cable connected to the correct GPU port? ( It happens.)
Mouse and keyboard plugged in (I've done it).

 

[joshchron1]

UPDATE:

I fixed it, turns out my cable that was connecting the button to the Motherboard went bad. I shorted out the pins where the cables were and it works fine now. Thank you to everyone who helped me out.