Computer Barely Attempts to Post, and Possible Hard Drive Issue...

This will be a rather lengthy post, so I apologize in advance. A couple of months ago I woke up to a messed up computer. The previous night it was working fine. The morning I woke up, I went to turn my computer on and it wouldn't post. The fans and LED's would start up for about a second and a half and would turn off, then try again continuously every couple of seconds. After researching into this I saw that it was most likely a power supply issue, motherboard issue, or processor issue. Here's how I've tried to troubleshoot the issue since then.

My first test was trying a new power supply. With the warranty I was able to do an in store replacement for a new one. I tried the new power supply to no avail.

After reading into it some more, I found out that processors don't die too often, so I decided to try out the motherboard. I called their tech support for troubleshooting and after a while they said to send it in since it was also under warranty. I sent it in and waited the two weeks to get another one back, only to have the same issue. I wasn't sure if I received another bad motherboard as MSI's policy is to send back a refurbished part, not your motherboard, and not a new one. With all of the bad luck I've had with this computer I thought that very well could have been the issue. (When I first put the computer together the PSU died in a week and then the replacement was DOA and then my graphics card died a month later)

Since I didn't have a means to test the other parts without spending money on new parts or waiting the two weeks to claim a warranty, I decided to take the computer to a diagnosis company. After their testing they told me the motherboard was bad. I then called to send in the motherboard again and explained the situation to MSI.

While waiting to get the motherboard back, I was able to meet up with a friend of mine to test my processor on his computer. His computer worked and the processor did as well.

I received a call from MSI where they tested the board. (Since it was the second time they said they'd test it and call me with what they found out.) They said the motherboard had no issues during their testing.

Today I got the motherboard back and put it back together again. This time it did somewhat the same thing, but it progressed a little further. A couple of times it's made it to the screen where you can go into the BIOS menu or boot menu. If you let it progress, I get a black screen with an error message that reads "Check cable connection. PXE-M0F Exiting PXE ROM". I looked into this and it said it's most likely an issue with the hard drive. I looked at the boot menu and the hard drive is number one on the boot list. The BIOS also recognizes that the hard drive is there. I went out a little earlier today and bought another hard drive to try and get past this menu. Unfortunately, it's still doing the same thing. If I do any sort of saving in the BIOS menu and reboot, I get the same issue as before where it continuously tries to boot but never posts.

With all of that, I'm completely lost. I'm debating on trying another tech company possibly, because I don't know what to do. Does anyone have any idea what to do or what to test?

This computer was put together October of last year. The graphics card was from December since the other died. The power supply is from November or so. Whatever is wrong now started in July of this year.

My build:

Nvidia Geforce GTX 970
Intel 4790k processor
Corsair 750W power supply
MSI Z97-G45 motherboard
8 GB Hyper RAM

The hard drive is a 1TB hard drive. I'm unsure of the brand.

Thanks for reading this, and for the help in advance.