Stable custom / home build freezes at BIOS screen (isolated to SSD C: drives) - Please help!

Hello everyone,
Thank you for taking time to look at my post. This seemed the most appropriate discussion to post in, my apologies if it is misplaced. I'm hoping you all could help me figure out what is/went wrong.

I've tried to make this as clear yet informative as possible.

The Synopsis (TL/DR version):

• - BIOS does not post.
  
  - Computer is custom home build, stable with nearly zero issue since 2012.
  
  - I think I am having a BIOS issue, or possibly a short out to my C: drive
  
  - Current C: drive is SSD 240GB, 1 year old. Replaced old SSD C: drive (64GB)
  
  - I've tried unplugging everything but RAM and CPU, same results.
  
  - When I unplug the C: drive, the computer boots - I can go to BIOS, and can boot to Win 7 CD
  
  - I installed my old SSD C: drive and computer initially booted several times, then failed.
  
  - After sitting 6 hours (off but plugged in) the old SSD C: booted again, I made an ISO, then it failed again on restart. Has not started since.
  
  - There was no data loss on old drive, so I don't believe the old drive failed/crashed.
  
  - New SSD C: drive has not booted since initial failure (~20 tries)
  
  - Being in the case, out of the case, different SATA cables, different SATA ports, and different power connectors, all meet with same results.
  
  - When either C: drive is unplugged BIOS will post.

Overview:
I am having issues with my custom build desktop. I built the core in 2012 and it has been quite stable since then. The computer restated the other day after a program update and would not load past the BIOS splash screen (not DEL, no boot menu, frozen before I can access). I have tried a number of things (details below), and read many posts on related issues, but I am still having issues and quite puzzled from the results of my troubleshooting.

My components (all core build devices except current SSD C: drive):

• ASUS PBZ-68-V LX mobo
  Intel i7 2600k (not OC)
  Cooler Master Hyper 212 EVO Heat Sink
  NVIDIA Quadro K2200 (PNY) (installed ~12/7/2015)
  Kingston SV300 240GC SSD (C: Drive - Win 7 - clone of old drive) (Installed 12/2014)
  *Old drive: OCZ Agility 3 64GB SSD (#2) (C: Drive - Win 7) (Reinstalled - see below)
  OCZ Agility 3 64GB SSD (#1 - not same as old drive) (L: Drive - Programs)
  HITACHI HDS721050DLE630 P/N: 0F13178 500GB HHD (V: Drive - Storage)
  Kingston RAM 8GB x 4 (32GB total)
  LG DVD Optical
  LG-Nortel ELO PCI100T Wireless PCI Card
  ANTEC 620W PSU
  Qty. 4 x 120mm chassis fans
  Windows 7 Professional (current with updates)

Peripherals (Attachment method)(install date) most are recently added:

• LG 27MU67 4K Monitor (Display Port)(~12/10/2015)
  Logitech M705 Wireless Mouse/K520 Wireless Keyboard Combo with USB Receiver (USB)(~11/1/2015)
  Logitech C920 Webcam (USB)(~12/7/2015)
  Yamaha RP-U100 Stereo Receiver (USB)(2012)
  Yiynova MVP22U Tablet Digitizer LCD Monitor (Wacom-like drawing tablet) (HDMI & USB)(12/18/2015)
  Inland PS/2 keyboard (for times like this)

Uninstalled Peripherals:

• VANTEC 4-port USB3.0 PCIe card with power port and 20-pin connector (computer did not recognize, caused chassis USB ports to not register - plan to return)
  Generic multi-card reader 5.25" bay (needed USB3.0 PCIe card to connect USB3.0 20-pin connector, other than that it functioned)

Background:
I built this computer years ago for my home office (CAD designer), but have recently given it some upgrades, mostly the result of this past Cyber Monday.

I have successfully installed all of the new hardware (except for the PCIe USB card and multi-card drive), including the Yiynova drawing tablet the night before. The next morning I was playing around with this, and installing some software that came with it and the monitor.

There seemed to be no problems with any of this, until the new software that came with my new monitors (LG Split Screen program) updated itself and requested a restart.

I clicked ok, the computer restarted and froze at the ASUS BIOS splash screen. I waited several minutes, then hard-restarted the computer again to the same results. I googled for answers, saw lots of similar symptoms, and started following troubleshooting advice.

• 
  - I first unplugged all USB devices, had same results.
  
  - I removed GPU and PCI cards, same results. I removed my hard drives and BIOS posted.
  
  - I then tried every combination of attachment, SATA cables, SATA ports, and power connectors
  
  - From this I determined that nothing affects the problem except having the C: drive connected.
  
  - BIOS will post with other drives and with all peripherals attached, but not with the C: drive connected.

At this point, other posts with similar issues seem to diverge, most finding different culprits (USB, RAM, etc). The best takeaway I have from other's advice is that it might be a short circuit to the C: drive somehow causing BIOS not to post.


( Here's where it gets more interesting: )
I have my old SSD C: drive (OCZ 64GB) which I connected outside the chassis. My new SSD drive is a clone of this one. The computer booted into Windows 7 and began recognizing new devices and updating, requiring a restart.

The computer restarted fine, yet my wireless USB keyboard didn't work (thought battery was dead, but confirmed since it is not), although the mouse did. I think I switched from the PS/2 to the USB keyboard during this reboot.

I restarted again, and attached the PS/2 keyboard, but this time BIOS did not post. I tried several more times to no avail. This is identical to the other C: drive

I left the computer off for about 6 hours (I believe it was still plugged into the wall), and when I tried to boot the computer went straight to Windows, except to inform me I had no keyboard installed. I plugged in the USB wireless keyboard, but it still did not register, although the mouse did. I then rebooted, connecting the PS/2 keyboard. The computer booed to Windows, I was able to make a disk image and put it on my V: drive. On the next restart, and ever since, I cannot get past the BIOS splash screen.

I have tried both drives since, and repeated some trouble shooting steps to be sure, but to no avail.


Some things I find perplexing:

• - The most perplexing thing of course, is why does BIOS fail to post with either C: drive attached?
  
  - The second most perplexing thing is why did my old drive work a few times, fail, work again, and then fail again?
  
  - The third, is why does BIOS post with out these attached?
  
  - I don't believe the problem is coming from my drives (like drive failure), because it happened to both of them.
  
  - It's not from the update which restarted, or any software, since BIOS freezes before Windows initializes, and the old SSD did not receive the same update.
  
  - Both my old drive and my new drive were held in a Thermaltake 3.5" to 2.5" bay mounting bracket. I was concerned that somehow the drives were being shorted through this, as the old SSD functioned when it was installed outside the chassis, but it makes no sense. The screws holding the drive in place would conduct current just the same as the bracket, and they metal on the side of the drives where they would touch the bracket is also the same part with the screw holes tapped into it. My other OCZ SSD (L: drive) is screwed directly to the chassis and has no issue.
  
  - Furthermore, neither SSD C: drive currently allows the computer to boot, whether inside or outside of the chassis.
  
  - I do not see anything inside my chassis that could be causing a short either. This is evidenced by the computer booting when C: drives are uninstalled.
  
  - Why is it the C: drives causing the issue? Two separate ones. Nothing else seems to matter, it's not cables, not ports, not peripherals, not power connectors. Nothing else being connected or disconnected matters.
  
  - How could it be so specific, yet somewhat intermittent, and not specific to either C: drive (as BIOS should only be checking that they are there, not what is on them - since it freezes before the boot menu option)? It seems like maybe it could be a BIOS problem somehow, but how? And how can I tell when the drive I need to check in BIOS is causing it to freeze before I can enter?
  
  - About the last thing I am concerned with is why the USB wireless keyboard didn't work while the mouse did. I don't know if it is related to the cause, just a symptom, or something else entirely.

So, I'm stuck. If I can't come up with other directions to try I'm calling "professionals" tomorrow, but I'm concerned they will be stumped, but after they charge me first.

Sorry for the lengthy write-up, but I wanted to be thorough for those of you who need the nuance and detail to help troubleshoot.

Thank you very much!!!