F5F Stay Refreshed Hardware Desktop The computer doesn't turn on when using SFX PSUs and the DP is connected. Does the ATX work?

The computer doesn't turn on when using SFX PSUs and the DP is connected. Does the ATX work?

The computer doesn't turn on when using SFX PSUs and the DP is connected. Does the ATX work?

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Beastboomer1
Member
169
09-09-2025, 07:17 AM
#1
Yeah, I understand. Odd behavior. Checked with two older Corsair ATX power supplies and it worked. If I connect a SFX PSU (Corsair or CoolerMaster) the red lights on my GPU turn on indicating no power. The PSU doesn’t need to be plugged into the wall at all. As soon as I connect the display’s DP port (like the 34" Ultrawide from Samsung), the lights come on. Photo: (see that it should show zero power) The main takeaway is: Asus ROG Crosshair VIII Impact CPU: AMD 5900X GPU: AMD 6950XT. If I press power with everything connected, fans spin briefly and then it stops. On the error screen, the RAM fault LED lights up but doesn’t attempt to boot. Disconnecting the DP or removing the power cable from the display fixes it—restart works too. Also tried a brand-new PSU that’s never been used before; same result. Ignore the case issue. I haven’t owned one for ten years. It’s fine. Great.
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Beastboomer1
09-09-2025, 07:17 AM #1

Yeah, I understand. Odd behavior. Checked with two older Corsair ATX power supplies and it worked. If I connect a SFX PSU (Corsair or CoolerMaster) the red lights on my GPU turn on indicating no power. The PSU doesn’t need to be plugged into the wall at all. As soon as I connect the display’s DP port (like the 34" Ultrawide from Samsung), the lights come on. Photo: (see that it should show zero power) The main takeaway is: Asus ROG Crosshair VIII Impact CPU: AMD 5900X GPU: AMD 6950XT. If I press power with everything connected, fans spin briefly and then it stops. On the error screen, the RAM fault LED lights up but doesn’t attempt to boot. Disconnecting the DP or removing the power cable from the display fixes it—restart works too. Also tried a brand-new PSU that’s never been used before; same result. Ignore the case issue. I haven’t owned one for ten years. It’s fine. Great.

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jejesko
Member
73
09-09-2025, 07:17 AM
#2
Have you used this DP cable before?
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jejesko
09-09-2025, 07:17 AM #2

Have you used this DP cable before?

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160
09-09-2025, 07:17 AM
#3
Used this cable for a long time. It's a DP 1.4 model from what appears to be a trustworthy manufacturer.
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TheWheatherMan
09-09-2025, 07:17 AM #3

Used this cable for a long time. It's a DP 1.4 model from what appears to be a trustworthy manufacturer.

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StephanKruger
Member
226
09-09-2025, 07:17 AM
#4
Uncertain in fact, perhaps because of these links: cablechick.com.au, ivanky.com, amd community.
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StephanKruger
09-09-2025, 07:17 AM #4

Uncertain in fact, perhaps because of these links: cablechick.com.au, ivanky.com, amd community.

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ngaiyan
Member
141
09-09-2025, 07:18 AM
#5
Welcome to the forums! To confirm: when using an ATX PSU, everything functions properly and the display shows images with a DP cable. However, with either SFX PSU, attempting to boot with a DP cable doesn’t work, but it does if you use an SFX PSU without a DP cable. Is this accurate? Please share the make and model of each PSU you tested. Does it POST when connected to an HDMI display? Can it start up with a DP plugged in but not linked to a screen? Have you tried connecting the DP cable to different ports on your GPU? Also, check if your monitor supports two DP inputs. You might want to try connecting the monitor to another power source (possibly needing an extension cord) from your PC. Do you have a UPS installed?
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ngaiyan
09-09-2025, 07:18 AM #5

Welcome to the forums! To confirm: when using an ATX PSU, everything functions properly and the display shows images with a DP cable. However, with either SFX PSU, attempting to boot with a DP cable doesn’t work, but it does if you use an SFX PSU without a DP cable. Is this accurate? Please share the make and model of each PSU you tested. Does it POST when connected to an HDMI display? Can it start up with a DP plugged in but not linked to a screen? Have you tried connecting the DP cable to different ports on your GPU? Also, check if your monitor supports two DP inputs. You might want to try connecting the monitor to another power source (possibly needing an extension cord) from your PC. Do you have a UPS installed?

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BattleHack
Member
156
09-09-2025, 07:18 AM
#6
Confirmed! Using Corsaid AX860i and VS550 works with my second screen via DP, using a DP-to-DVI adapter. It posts when the DP is plugged in but not connected to a display. I've tried various ports and circuits, but it's tricky. Would need a long enough cable. No UPS required.
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BattleHack
09-09-2025, 07:18 AM #6

Confirmed! Using Corsaid AX860i and VS550 works with my second screen via DP, using a DP-to-DVI adapter. It posts when the DP is plugged in but not connected to a display. I've tried various ports and circuits, but it's tricky. Would need a long enough cable. No UPS required.

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Twanneman81
Member
92
09-09-2025, 07:18 AM
#7
Other updates: It keeps restarting unexpectedly during gameplay. This issue also messed with the GPU driver before. I'm planning to replace the DP cable and check if that helps.
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Twanneman81
09-09-2025, 07:18 AM #7

Other updates: It keeps restarting unexpectedly during gameplay. This issue also messed with the GPU driver before. I'm planning to replace the DP cable and check if that helps.

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Blue_Fox_Lady
Member
194
09-09-2025, 07:18 AM
#8
You've only tested two of the four items. Which sound did you use? Are you asking about the VS550 being orange or grey? If it's orange, it should be discarded.
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Blue_Fox_Lady
09-09-2025, 07:18 AM #8

You've only tested two of the four items. Which sound did you use? Are you asking about the VS550 being orange or grey? If it's orange, it should be discarded.

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I_Pux
Member
60
09-09-2025, 07:18 AM
#9
Consider starting with the HDMI cable first to check compatibility. If that doesn’t work, use a multimeter to perform a continuity test on the 20th pin. You might need a needle tip for better contact due to the small slot and pins being somewhat deep.
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I_Pux
09-09-2025, 07:18 AM #9

Consider starting with the HDMI cable first to check compatibility. If that doesn’t work, use a multimeter to perform a continuity test on the 20th pin. You might need a needle tip for better contact due to the small slot and pins being somewhat deep.

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flashbangJDE
Junior Member
7
09-09-2025, 07:18 AM
#10
I apologize for the error. I found the most compact HDMI cable available, and it seems to be working properly now. I plan to try out some games to check its performance.
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flashbangJDE
09-09-2025, 07:18 AM #10

I apologize for the error. I found the most compact HDMI cable available, and it seems to be working properly now. I plan to try out some games to check its performance.

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