[Help] PC has no display signal

[wind77]

Using PC, and suddenly the monitor entered power saving mode due to loss of video signal.

1. With VGA card still on MB, swapped hdmi cable to iGPU, no signal.
2. Swapped to new VGA card, hdmi cable on VGA card, no signal, MB LED showed VGA error.
3. Removed power cable to VGA card, hdmi cable on iGPU, signal restored.
4. Tried on 2nd PCIe slot, no signal from both VGA cards (when powered), MB LED showed VGA error.

Given the situation, what is the likely faulty part?
PSU? MB? VGA card?

Help appreciated!!!

 

[grimfan]

Using PC, and suddenly the monitor entered power saving mode due to loss of video signal.

First thing, did you change the bios setting to reflect the GPU you want in each of the below configuration?

1. With VGA card still on MB, swapped hdmi cable to iGPU, no signal.

No signal likely due to GPU not set to iGPU.

2. Swapped to new VGA card, hdmi cable on VGA card, no signal, MB LED showed VGA error.

"New" meaning you bought a new GPU or you are using GFX card you know is working?

Check if GPU is seated properly in PCI-E slot. If so, possibly mainboard PCI-E issue or PSU not supplying power to GFX card properly.

3. Removed power cable to VGA card, hdmi cable on iGPU, signal restored.

If this configuration is working, seem like mainboard or at least not the entire mainboard got issue. Mainboard likely auto switch to iGPU when you disconnected power cable to GFX card.

4. Tried on 2nd PCIe slot, no signal from both VGA cards (when powered), MB LED showed VGA error.

Both VGA cards? Do you mean GFX card and iGPU? If so, monitor connected to which output? If GFX card, it seems like original issue.

My conclusion is either PSU power issue to GFX card or mainboard PCI-E problem.

 

[yusoffb01]

If u replaced graphic card still have problem, then is PSU issue

 

[wind77]

First thing, did you change the bios setting to reflect the GPU you want in each of the below configuration?

There is no change in bios settings required. If both discrete GPU and iGPU are present, both will work simultaneously.

"New" meaning you bought a new GPU or you are using GFX card you know is working?

It's a new GPU. But since I have not installed it previously, I can't say I know it's working.

Both VGA cards? Do you mean GFX card and iGPU? If so, monitor connected to which output? If GFX card, it seems like original issue.

Both VGA cards. iGPU won't work as long as one VGA card is installed and powered, since the MB cannot completes self check, and reports VGA error.

Original issue, you mean PSU/PCIe problem, or VGA problem?

 

[grimfan]

There is no change in bios settings required. If both discrete GPU and iGPU are present, both will work simultaneously.

They should work simultaneously but the primary boot GFX is different thus you get the no display problem. If you intentionally set the primary display to iGPU, technically since your iGPU is working, you won't get no display.

It's a new GPU. But since I have not installed it previously, I can't say I know it's working.

Then it should be working. Does this GFX require additional power? If not, like I mentioned, it means not enough/no power is being delivered to it when it is the primary display.

Both VGA cards. iGPU won't work as long as one VGA card is installed and powered, since the MB cannot completes self check, and reports VGA error.

Original issue, you mean PSU/PCIe problem, or VGA problem?

The original issue I meant is the original symptom you got "no display"

Likely either PCI-E problem or no/not enough power to GFX.

 

[wind77]

Ok, got a loan GFX card and PSU tester from friend.
PSU confirmed working.

On my friend's PC:
My current GFX card didn't work.
My new GFX card worked.
Loan GFX card worked.

On my own PC:
My current GFX card didn't work.
My new GFX card didn't work.
Loan GFX card worked.

So I guess this means both my Mobo and PSU are safe.

New GFX card not working on my PC - compatibility issue?
Z68 series Mobo, 2 PCIe slots, only use 1 for the GFX card.
New GFX card is R9 290X.
PSU 750W, power is enough, I believe.
But no matter which slot of PCIe I use, Mobo always report VGA failure, and cannot boot into OS.
Without change in BIOS, installing loan GFX card worked immediately.

How should I troubleshoot now?

 

[grimfan]

Ok, got a loan GFX card and PSU tester from friend.
PSU confirmed working.

On my friend's PC:
My current GFX card didn't work.
My new GFX card worked.
Loan GFX card worked.

On my own PC:
My current GFX card didn't work.
My new GFX card didn't work.
Loan GFX card worked.

So I guess this means both my Mobo and PSU are safe.

New GFX card not working on my PC - compatibility issue?
Z68 series Mobo, 2 PCIe slots, only use 1 for the GFX card.
New GFX card is R9 290X.
PSU 750W, power is enough, I believe.
But no matter which slot of PCIe I use, Mobo always report VGA failure, and cannot boot into OS.
Without change in BIOS, installing loan GFX card worked immediately.

How should I troubleshoot now?

Don't get me wrong, didn't say your PSU not working nor not enough power. Saying that either no/not enough power to GFX or PCI-E issue.

Since your loaner GFX works, likely not PCI-E issue. Which come back to the question of power. Loaner GFX is what model and need extra power connector from PSU?

If no need then suspect power delivery issue from the rail/connector from PSU to GFX. Modular PSU?

If not, it's going to be complicated on what exactly is wrong liao.

 

[wind77]

Oh, haha.
It was my friend's suspicion on the insufficient power or faulty PSU.
So I put it upfront to help narrow down the troubleshooting.

My current GFX is a HD6950, requires 6+8 pins to power.
My new GFX is R9 290X, also requires 6+8 pins to power.
The loaner GFX is HD6850, 6 pins only.

Unfortunately, the PSU tester i loaned, its connector only capable of testing 6 pins, but not 8 pins.
The 6 pins from both PSU cables works, but yeah, the extra 2 pins maybe faulty.

Using modular PSU.
Will check diff connecting ports and PCIe cables on PSU.
Hopefully this is just PCIe cable or PSU issue.

 

[wind77]

Today's troubleshoot:

My PSU has 2 sockets for PCIe devices.
On PSU's socket (say socket A) for PCIe device , I used new PCIe power cable, connected to new GFX, not working.
On PSU's socket (socket B) for PCIe device, I used new PCIe power cable, connected to new GFX, not working.

Really clueless on what to do next liao...

 

[grimfan]

Today's troubleshoot:

My PSU has 2 sockets for PCIe devices.
On PSU's socket (say socket A) for PCIe device , I used new PCIe power cable, connected to new GFX, not working.
On PSU's socket (socket B) for PCIe device, I used new PCIe power cable, connected to new GFX, not working.

Really clueless on what to do next liao...

Try alternating socket A and B for loaner GFX which only use one 6-pin power connector.

If one works and the other doesn't you have your answer, one of the rails is dead.

 

[wind77]

Try alternating socket A and B for loaner GFX which only use one 6-pin power connector.

If one works and the other doesn't you have your answer, one of the rails is dead.

Have done this.
Both rails works on loaner GFX.

 

[jtjt00]

........
My current GFX is a HD6950, requires 6+8 pins to power.
My new GFX is R9 290X, also requires 6+8 pins to power.
The loaner GFX is HD6850, 6 pins only......

From the above, the loan GPU used less power compared to your current and new GPU. Get a spare PSU to test.

 

[grimfan]

Have done this.
Both rails works on loaner GFX.

At least know both rails are at least working.

Now is to find a way to test your 8-pins connector liao. But what are the odds that suddenly a connector will fail while using halfway?

How old is your PSU by the way?

 

[wind77]

At least know both rails are at least working.

Now is to find a way to test your 8-pins connector liao. But what are the odds that suddenly a connector will fail while using halfway?

How old is your PSU by the way?

PSU bought in 2011, Seasonic 850w - opened the original packaging box and realized it is 850w and not previously assumed 750w.
It has 2 PCIe rails.
One PCIe rail connected to Mobo - if not, Mobo cannot fully boot.
Have tried swapped to the other PCIe rail - Mobo booted with no issue.
That's why I think both PCIe rails should be working fine.

 

[grimfan]

PSU bought in 2011, Seasonic 850w - opened the original packaging box and realized it is 850w and not previously assumed 750w.
It has 2 PCIe rails.
One PCIe rail connected to Mobo - if not, Mobo cannot fully boot.
Have tried swapped to the other PCIe rail - Mobo booted with no issue.
That's why I think both PCIe rails should be working fine.

Your PSU fully modular ah?

On mine a semi-modular one, I have a non-modular PCI-E connector which I used for my mainboard. My GFX is using two modular connectors.

If yours fully modular you should have many other PCI-E rails to try no?

 

[wind77]

Your PSU fully modular ah?

On mine a semi-modular one, I have a non-modular PCI-E connector which I used for my mainboard. My GFX is using two modular connectors.

If yours fully modular you should have many other PCI-E rails to try no?

Fully modular.
However, only 2 rails for PCIe.

Just checked the mobo manual and realized that the mobo doesn't require additional PCIe power.
So wondering why 1 rail is used by mobo...
Prob have to check again tomorrow.

In any case, the new GFX card has been tested on both rails and still not worked...