Optiplex 3010 won't work with GTX 1660 Super

Depending on the form factor of your 3010 the largest PSU you could have is 265W. The GTX 1660 Super requires a PSU of 450W. You simply do not have the required power to run the card. Plugging in that power plug from the PSU puts too much of a load on the PSU hence the system shuts down.

Re: but the moment I plug in the 8 pin pci-e power cable the whole computer shuts off and won't turn on

which psu power rating do you have in the 3010?  If it has an 8 pin, sounds like you have upgraded psu.  You are not supposed to leave the gpu 8 pin unplugged without supplementary power and turn on the pc, then hot plug in the 8 pin while there is power in the PC going into the gpu via the PCIe slot.  The correct procedure is to plug in the 8 pin when pc is powered off, then turn on the pc.

I know. When I do this it still doesn't work. It just doesn't turn on. Do you think this could be because of the BIOS version?

I am not sure BIOS version would make a difference.  Another user's experience with 1080 may not necessarily apply to your case. 

First confirm you can get good video from the integrated on board video when 1660 Super is not installed in pc.  Do you have a simple video card that does not require 6 or 8 pin to test the PCIe slot.  If so, test for discrete video card signal using the simple card.

You see, PC does not turn on is a different issue from PC turns on but no video (No POST).  Need to first confirm PC can turn on and produce basic normal video either from on board VGA or simple discrete video card before proceeding to next diagnostic step.

If PC does turn on without 1660 Super, then which upgraded psu do you have in the PC?  Need to figure out which 8 pin of this PSU you are using.

Re: when I have my GTX 1660 Super connected to my motherboard it works perfectly fine,

When you say it "works fine" do you mean you are getting video from onboard video or 1660S?  If you install 1660S without 8 pin and power on PC, PC may not detect the card, or may send a loud beep warning no power to card, depending on the motherboard.  Either way that is not correct way to use 1660S.

I am using a 80+ 500 Watt Thermaltake PSU.

that is a very good psu.  user benchmark shows 1660S is compatible with 3010.  Dell OptiPlex 3010 Performance Results - UserBenchmark

If PC does not turn on at all with 1660S installed and 8 pin plugged in, uninstall 1660S, use on board video to get in BIOS.  check if secure boot is disabled.  

http://sgwmscdnimages.azureedge.net/48/8-25-2019/94256212511536Daey.JPG

Secure Boot: Enable Allows you to enable or disable Secure Boot feature
• Disable
• Enable

do you have a simple video card to test the PCIe x 16 slot?

I do not. And secure boot is enabled, should I disable it?

Yes try disable secure boot then install 1660S with 8 pin plugged in then power on PC.

If the following is your psu, I assume you would plug the PCIe (6+2 pin) in 1660S.  Which model is your 1660S?

Smart 500W (thermaltakeusa.com)

Umm. I don't know how to turn my Optiplex 3010 on with shorting it. I don't have a case and it turns on when I flip the PSU on. Do you know how I could turn it on with a screwdriver pin touch?

Nevermind, I figured out how to turn it on with the shorting pin way. I tried the secure boot and it still did not work. My GPU model is an ASUS GTX 1660 Super 6GB single fan. Model number - E2483U-C or L30YZ00S344PWH

I just did some research and turns out I could test my PCI-E x16 slot with my PCI-E x1 wifi card, and my wifi card worked in it. I updated my BIOS and that didn't fix my issue. I'm starting to think that my PSU is the problem, but every other part works. My computer works with integrated graphics but not my GPU.

The GTX 1660 SUPER is a 125w card.  GPU's don't just take power from the 12v rail.  There has to be enough power on the 3.3v/5v rails.  The PSU you're using only has the same amount of power (100w) on those rails as the original Dell 275w PSU that's for the 3010 MT.

From the Optiplex 3010 Tech Guide: 

Thermaltake 500w PSU:

Thermaltake 700w PSU:

EVGA BR 500w PSU:

EVGA BR 700w PSU:

I'd put my money on that it's the PSU not having enough power on all of the rails.  Try one with at least 120w on the 3.3v/5v rails.  150w, which comes with the EVGA BR 700w PSU, may be the safest bet;.and it doesn't cost that much more.

Note that the 700w Thermaltake still only has 120w on the 3.3v/5v rails.

Also note the +5vsb rail.  It's 4a for Dell PSU, 2.5a for the Thermaltake's, and 3a for the EVGA's.

Now you should have what you need to make a well informed PSU decision. : )  Aftermarket PSU's may boast more total power, but often skimp on other rails.

that is strange.  I can not believe that the psu would stop the 1660S working. 

can you verify whether the pc can turn on with 1660S installed and just no video?  If so that is No POST.  If so, test video output from integrated VGA while 1660S is installed with 8 pin plugged, in case for some strange reason PC is not switching automatically to discrete GPU.  If you still get normal video from integrated VGA while 1660S is powered on in PC, that is a clue.

On the other hand if your PC can not power on at all with 1660S installed with 8 pin plugged in, it is a different issue.

You're talking about the power cord, right?  Either way, a cord/cable with a loose connection could be a fire hazard.  Replacing it is definitely worth a shot.

I think I have figured out the problem, and yes it works when it is connected to the motherboard with no 8 pin power. I ran into a problem earlier where my PC would not turn on at all no matter what. Turns out the cable that I connect to the back of the power supply only worked at a exact angle. I was reading another forum and this was the problem for someone else like me. I have to replace that cable I'm pretty sure. When I tried my card on my system that I used to use with everything the exact same except for the motherboard and CPU, my GTX 1660 Super would not allow the power supply to turn on. I'm guessing the power supply cable broke somehow and is restricting all of the power needed for the system because the GPU takes a lot of wattage. Do you think changing the cable could fix my problem?