Posted 20 September 2012 - 04:37 PM
From just a very rough guess, I would assume that yes your hard drive is having some issues, because it isn't able to POST (Power on Self Test). Technically speaking, a HDD isn't necessary for a computer to run. When you unplugged your HDD, the computer was able to "run" sufficiently enough to give you a few options from the mobo os. I'm a little confused though as to whether or not you did a 2 step troubleshooting procedure or not. From the sounds of it, you reseated your RAM AND unplugged your hard drive. That's all well in good, but now we don't know if it was just the RAM out of whack, the hard drive, or both. I typically try to troubleshoot by only changing one thing at a time. If ti works, I know that is the problem part, if not, the part is most likely good.
If you did a 2 step procedure, simply try plugging your hard drive back in. The reason I say this is because when a hard drive typically craps out, the platters or disk head fail, and the drive will simply just not be able to show its data, but the computer would still "boot up" (Usually giving an error about there being no usable disk or no os installed or something along those lines). If this works, then you should be back in business.
If not, then you will most likely need to install a new hard drive and reinstall the os. The raid drivers just means that your mobo natively supports raid, and that would be how you would set it up. The freedos command prompt sounds like a very simple I/O os installed on the mobo that would let you run some very simple commands (Think MS-DOS just not from Microsoft.) Basically, after you completed your last troubleshooting step before getting to this, you "fixed" your computer. Now if you can't get the HDD to be recognized, you need to replace that.
Installing a new OS is as simple as popping in the OS install disk. If you have recovery disks from the manufacture (your system looks self built so I doubt it) then use those. If not, use the disk you used when you first installed it. If someone else installed it, ask them, or at the very last option, go buy a new copy of windows. You may be able to find a closeout sale on W7, and if not you crashed at the right time because its W8 time anyways. If you don't really want to drop any money on an OS, there's plenty of very viable free options like Ubuntu, which would take a little bit of a learning curve, but no more than what will be required to learn W8, and you would save yourself a few extra bucks for your wallet.