This is probably a more expert question than what you guys are used to. I have been lurking around here long enough to know you guys are my best bet. Maybe you guys can at least point me in the right direction.
Story: I fix/refurbish graphics cards on the side. It is mostly as a hobby... not really to make any money. I fixed a 480 GTX and a 960 GTX recently. I tested them in my test rig which is just an old 939 socket AMD board and a beefy 850W power supply that can do the rest. It's enough to get a picture. My son's GPU crapped out recently so I decided to upgrade him. I put my test rig power supply in his computer since he didn't have an 8 pin pcie connector. I started with the 480. Got the driver installed and everything going smooth. All the sudden, instant shutdown. Computer wouldn't even power up with the 480 Installed. So I assume it's the card since it was a long shot fix anyway. It was missing like 20 surface mounted pieces...
So, I throw the 960 GTX in next. Same story. Works for a while, then, a sudden shutdown and can no longer start the computer with it installed. So it was the power supply the whole time. To prove it, i threw in a gt 430 and got random shutdowns. So I toasted 2 video cards over it. I put both these cards in my rig and was not able to boot my rig either so now I have 2 GTX cards exhibiting identical behavior. I don't see any obvious signs of damage on either of the cards.
So my question: Does anyone know where to start with these cards? I actually found a loose screw in the PSU later so I can assume the cards took a short through the PCIe cord. I am capable of swapping out any piece on the board if necessary. I even have a spare GPU for the 480. I feel like if I can diagnose one, I can assume the other card has the same problem. Of course, making assumptions is how I got into this mess in the first place. I just don't want to give up on these cards just yet.
Edit:
Well I know the issue is in the graphics cards. His computer is now running fine with the gt430 and original PSU. My computer would not power up
either of these graphics cards. But good now with my original GPU. My PSU would support these cards. And by not powering up i mean nothing. The CPU fan does about half a spin. Then nothing. I was hoping there was a if you juice your graphics card this piece will go first kind of answer. I did inspect the boards decently but didn't see anything specific. The 960 has an after market cooler that is pretty open. I'll take a closer look tomorrow and get back to you guys. And if all else fails maybe we do the oven trick =D
Edit 2:
I've removed both heat sinks and thoroughly inspected both boards. Nothing stood out. I think it is time to accept their fate. What killed them could have come through the PCIe slot as well. This broadens the list of possible culprit pieces to essentially everything on the board. Or at least whatever could be bad that would cause the computer not to power up... Thanks for the responses...
Edit 3:
So I have been doing a lot of research on how power is regulated through graphics cards. I learned a lot here. All the information on that site pointed me toward the VRM section of the board. Also, I found this on Tom's Hardware. TLDR: a blown MOSFET will almost always be a shorted MOSFET. If a power supply detects a short, it will not allow the computer to start. So, I took another look at the boards. I didn't see anything on the 480, but look what I found on the 960.
If you look closely, you will see a pimple on that MOSFET in the red box. This is most likely the issue. I will have to test the MOSFETs on the 480 since I have replacement pieces for that one, and I will have to order one for the 960. Will update when fixed...
Story: I fix/refurbish graphics cards on the side. It is mostly as a hobby... not really to make any money. I fixed a 480 GTX and a 960 GTX recently. I tested them in my test rig which is just an old 939 socket AMD board and a beefy 850W power supply that can do the rest. It's enough to get a picture. My son's GPU crapped out recently so I decided to upgrade him. I put my test rig power supply in his computer since he didn't have an 8 pin pcie connector. I started with the 480. Got the driver installed and everything going smooth. All the sudden, instant shutdown. Computer wouldn't even power up with the 480 Installed. So I assume it's the card since it was a long shot fix anyway. It was missing like 20 surface mounted pieces...
So, I throw the 960 GTX in next. Same story. Works for a while, then, a sudden shutdown and can no longer start the computer with it installed. So it was the power supply the whole time. To prove it, i threw in a gt 430 and got random shutdowns. So I toasted 2 video cards over it. I put both these cards in my rig and was not able to boot my rig either so now I have 2 GTX cards exhibiting identical behavior. I don't see any obvious signs of damage on either of the cards.
So my question: Does anyone know where to start with these cards? I actually found a loose screw in the PSU later so I can assume the cards took a short through the PCIe cord. I am capable of swapping out any piece on the board if necessary. I even have a spare GPU for the 480. I feel like if I can diagnose one, I can assume the other card has the same problem. Of course, making assumptions is how I got into this mess in the first place. I just don't want to give up on these cards just yet.
Edit:
Well I know the issue is in the graphics cards. His computer is now running fine with the gt430 and original PSU. My computer would not power up
either of these graphics cards. But good now with my original GPU. My PSU would support these cards. And by not powering up i mean nothing. The CPU fan does about half a spin. Then nothing. I was hoping there was a if you juice your graphics card this piece will go first kind of answer. I did inspect the boards decently but didn't see anything specific. The 960 has an after market cooler that is pretty open. I'll take a closer look tomorrow and get back to you guys. And if all else fails maybe we do the oven trick =D
Edit 2:
I've removed both heat sinks and thoroughly inspected both boards. Nothing stood out. I think it is time to accept their fate. What killed them could have come through the PCIe slot as well. This broadens the list of possible culprit pieces to essentially everything on the board. Or at least whatever could be bad that would cause the computer not to power up... Thanks for the responses...
Edit 3:
So I have been doing a lot of research on how power is regulated through graphics cards. I learned a lot here. All the information on that site pointed me toward the VRM section of the board. Also, I found this on Tom's Hardware. TLDR: a blown MOSFET will almost always be a shorted MOSFET. If a power supply detects a short, it will not allow the computer to start. So, I took another look at the boards. I didn't see anything on the 480, but look what I found on the 960.
If you look closely, you will see a pimple on that MOSFET in the red box. This is most likely the issue. I will have to test the MOSFETs on the 480 since I have replacement pieces for that one, and I will have to order one for the 960. Will update when fixed...
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