Dell 24 to 8 Pin

[BlueNostromo]

Hello, my friend and I tried to get a Dell 3020 working with a DIY 24 to 8 pin connector using some of the pictures of the adapters and other user found pinouts. We are having some problems. The computer will turn on, but the green PS_ON_N needs to be connected to ground manually to boot at all. We have left this pulled to ground. The computer turns on and works fine except the GPU gets hot at idle and the fan will only be 0% or 100%. Any help?

 

[trents]

The OEM proprietary blues.

 

[Bill_Bright]

The OEM proprietary blues.

And why building your own is the only way to go. This may very well be your PS_ON_N grounding issue but I think your GPU fan issue is a separate issue. The GPU's fan speed should be controlled by the card's own heat monitoring circuits.

 

[trents]

What video card are we talking about, Bluenostromo? Did it ship with the computer? Is this like a reburbished unit? There are a lot of those Dell 320s sold as refurbs.

 

[Dolk]

Hmmm something I may be able to help with. Our PSUs typically have an AUX and MAIN voltage output for 12V that is controlled by a smart voltage controller. Basically it will sequence some to most of the voltage rails in your system to turn on at certain times during bootup. This all happens within a second, but there are quite a lot of things that need to be checked and powered on during this ~1sec.

I can't share where to best strap this PS_ON_N, but I can give some general advice. The PS_ON_N is an input into the PSU to turn on the MAIN 12V rails. If these rails are on at the start, the GPU and other devices that require the BIOS to be awake first may not act correctly or in an unexpected behavior due to the design of the sequence I mentioned. If you have a DMM or an oscilloscope, you can probe around the 8pin power connector to figure out which is the PS_ON_N signal by simply applying the power button and waiting for one of those signals to transition from a high voltage (3.3V or 5V) to 0V. If you find that transition, that will most likely be the PS_ON_N signal. If you don't have those tools at hand than you'll be a bit out of luck.

 

[BlueNostromo]

https://www.dell.com/community/Desk...RIBLE-Optiplex-9020-Power-Supply/td-p/4462971

https://www.ebay.com/itm/24Pin-to-8...sh=item41fe623e1f:g:qI8AAOSwenJb96-S&LH_BIN=1

https://i1.wp.com/www.modmag.net/pic/articles/guides/led-connection/molex-pinout.png

These are the sources I had used. The weird thing is that when the I have it connected using the pinouts detailed by the users and following the pictures of adapters it will still not turn on. I have to force it on by connecting the PS_ON to ground. I also read that there is a sequence required for PS_ON/PS_OK and just forcing it to ground all the time might put things in a bad state. I have a suspicion that the graphics card might be getting full power at all times due to this. We are going to try DDU and different drivers to see if the graphics card will function normally. We dont want to kill it.

 

[Dolk]

Sounds like you have an issue with the system than. There are smart controllers monitoring power and and other important sensors that will determine if it can turn on the PSU at all. If the GPU issue and the PS_ON_N refusing to go low with a "good" 24 to 8 pin adapter are related than the system may not be happy with the current config; something is broken and it may not be the adapter.

I'd double check the PS_ON_N signal with your 24 to 8 pin adapter cable. Make sure it is driven to ~0V. If it never toggles than that means the smart controller isn't satisfied with the current conditions. Do note that a DMM may not capture any transitions that are faster than a few hundred-milliseconds. They are meant to measure constant voltages, not fast switching voltages. So any attempts of the PS_ON_N signal being driven low but than back high by the smart controller may not be readable via a DMM.