PC turning on but no Signal to monitor

[Witzprinz]

Hello, 

 

I am currently helping my friend repair his PC. His PC was running fine the first time he got it but after 2-4 months it started having problems, the screen was not working sometimes but other times it did. He didnt really think to much about it untill it never showed a signal. So then he brought his pc to me and I started Troubleshooting. I first checked if it worked on my monitor, I tried using dvi and Hdmi but none of them worked so then I opened the pc. btw the pc is a dell exone with a core i5 3470 and an AMD 280. I first cleaned the pc the ram connectors the ram itself and the gpu. I tried running it again but there was no signal but the fans were spinning and while the gpu fans were spinning wierdly i.e they would spin for a second then stop spinning I think its normal when it is not on load. So then I tried swaping all the parts which I could from his pc to mine. I tried the gpu and it worked without any issues on my pc. then I checked the ram but it didnt work because my pc is a lenovo thinkcentre with a motherboard that is locked to some specific memory or that is my guess. I couldnt try the cpu because of the socket differences, I didnt bother checking the psu because it is a 2-4 month old 500watt EVGA power supply. I think the PCIE slot is broken but I think there is also some other problem because his motherboard has a dvi connector. and I thought I would at least check on task manager if the gpu was really not recognized but the dvi port didnt work, so now I am confused because I dont think that his cpu could have died. So if you know how to diagnose a cpu in this situation then please do tell. and if you also know how to fix or diagnose a faulty PCIE slot then please do also tell. Any help would be great.  

[Awesome84]

My first guess would be a bad RAM.

[skNDstry]

1. Any beeps? You may have to listen very carefully. 

2. Do you have a diagonistic card? If you do, try plugging it in, and see what it says.

3. Swap out the psu for a known working one. These are gory.

4. As 

3 minutes ago, Awesome84 said:

My first guess would be a bad RAM.

try getting a known working RAM stick. or if he has many, try one-by-one.

5. switch the GPU. This is risky though.

[Witzprinz]

Thanks you guys for your responses I have found out the issue and it was a mix of bad ram and one of the ram slots was not functioning. So one of the 8gb ram sticks was not working and the connector for the working one was broken as well, so switching their positions made the pc work again. Thanks for taking your time to answer my questions