Startup hard drive errors

[msacco]

Hello, I have a weird problem with my computer and I'd like some ideas of what the problem could be, sometimes I am getting some errors about my hard drive(such as "A disk read error occured", "Hard Disk Error", "Boot Device Not Found", "Reboot and Select proper Boot device or Insert Boot Media in selected Boot device"), its a different error each time, but if I remember right its always the hard drive, but I simply fix that error by just playing with the sata cables a bit and then it works.
It usually happens randomly, with no reason I can see, but my computer just start to stuck and freeze, and most of the times end up in a blue screen run error, then I restart my pc and have the problem, play with the sata cables and then my pc runs well again.
I've had this problem for years, even on my old computer, which is very very weird, my brother also has that but very rarely. I bought a new hard drive like 6 months ago(still using my old hard drive for more storage, but I tried connecting only one at a time), but the problem is still there, which makes me think that it might not be the hard drive's problem.
I tried switching the sata cables, but it doesn't help, thought of switching the sata power cables, but it comes from the PSU and have no way to do that.
I am pretty lost with no ideas of what it could be, the fact that it happened in my old computer as well, and in my new computer with new hard drive, is just too weird to me.
Here are my specs if needed:
i5 3470
Radeon 7850 HD
B75MA-E33
Western Digital Blue WD10EALX 1TB 7200 RPM(old hard drive)
Seagate Desktop HDD ST2000DM001 2TB 64MB(new hard drive)
12 GB, 4 GB stick + 8 GB stick(Yes, I know its not very good)
Win 7 Ultimate 64 bit

Thank you for the help and sorry for the long post.

 

[hang-the-9]

You can get a drive scanning utility from the drive vendors and scan the drive for errors.
Could be a motherboard issue if the drives test good. The power supply should have a number of SATA power cables, try another set.

 

[msacco]

You can get a drive scanning utility from the drive vendors and scan the drive for errors.
Could be a motherboard issue if the drives test good. The power supply should have a number of SATA power cables, try another set.

Thanks for the answer, I don't know if it is a good software, but I have tested both my hard drives using SeaTools and everything was good.
I also had a very weird problem yesterday, I started my computer, and nothing was up on the screen, no starting "beep" either, and after about 15 seconds my computer turned off, then on again, it just kept doing that non stop.
I checked all the connections, and everything was good, I even disconnected everything to check maybe something is circuiting, but even when almost only the motherboard was connected, I had the problem.
I tried connecting another PSU(old PSU), and it actually seemed to work, it didn't turn off after 15 seconds, but after a few minutes it started doing that as well. I decided that becuase its an old PSU it might not indicate well whats the problem and decided to take my brother's PSU as well. I connected it, and everything seemed to work, so I thought its probably my PSU. But then I tried connecting my own PSU once again, and everything just worked as it should. I think that it might be the motherboard, if there is even something thats not good, but that was very weird..
So after this long post, is there any way to check if the motherboard is not working well?

 

[hang-the-9]

Your PSU may have just had a chance to reset for a while, see how things work in a few days. The only good test for a motherboard would be to swap it and see if the issue goes away unless some components clearly don't work like USB ports or audio.

 

[msacco]

Your PSU may have just had a chance to reset for a while, see how things work in a few days. The only good test for a motherboard would be to swap it and see if the issue goes away unless some components clearly don't work like USB ports or audio.

Thank you, so far my computer works well with no problems at all. Regarding the hard drive, if there are no errors in my hard drive, what else could be the problem? only the motherboard?