PC randomly doesn't boot after sleep + no POST + BSOD

Edit: I might have found the culprit of the BSOD, so I only need help with the POST/sleep issue specifically (main thread)

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I'm having a series of problems I'm just losing my head over.

1) First off, I never had a single stability problem while the PC is running, in fact it's quite new and I've been using it without any issues. However, as soon as I put it to sleep there will be a chance that it will simply not wake up next time, regardless of sleep duration, forcing me to turn it off and on again.

2) When this happens, it will take some random attempt at rebooting it because sometimes the POST will just not happen, and I've tried every combination of button press/USB unplugging/power cut.

3) When it decides to boot, it sometimes will fire a Plug & Play BSOD during the Windows startup, and the randomness start again. Again, tried any combination of reseating/unplugging/changing any USB port and devices/etc.

4) When it finally decides to boot Windows, I browse through my minidumps and see that while I had lots of BSODs, Windows decided to just generate only one dump, i.e. only the last BSOD that happened got dumped as if the others never existed. And even after multiple events, I simply can't piece their info together to find the culprit. The only thing they have in common (using BlueScreenView to parse through them) is the following faulty module stamp:

Code:

ntoskrnl.exe	ntoskrnl.exe+175af0	fffff800`04aXXXXX	fffff800`0XXXXXXX
0x005ec000	0x5609efa0	29/09/2015 03:55:44	Microsoft® Windows® Operating System
NT Kernel & System	6.1.7601.19018 (win7sp1_gdr.150928-1507)	Microsoft
Corporation	C:\Windows\system32\ntoskrnl.exe

With the only difference being the address,

Code:

fffff800`04aXXXXX	fffff800`0XXXXXXX

The other faulty modules are always different; rdpencdd.sys, nvhda64v.sys, usbhub.sys, CompositeBus.sys, raspppoe.sys, ftusbload2.sys, HWiNFO64A.SYS, vpcvmm.sys....

(I can upload all the minidumps if needed.)

After that, I get everything working as usual as if nothing ever happened; the PSU voltages seem to be fine, the motherboard/GPU/CPU seem to work correctly, I can play games, watch videos, develop apps, fill 16 gb of RAM no problem...

What is this? A software issue? A hardware issue? A faulty Windows installation? A corruption in the PNP subsystem? I'm simply losing my head!

My specs are as following:

- Windows 7 Professional SP1 (I have some updates due)
- Corsair CX500M 500 Watt PSU
- Gigabyte 990FXA-UD3
- Zotac GeForce GTX 970
- AMD FX-8350 4.00 GHz
- Corsair Vengeance 16-GB kit RAM
- Cooler Master Hyper 212 EVO
- An old 300 GB Seagate ST1000DM003-1SB10C
- A newer 7200 RPM 1TB Seagate Barracuda ST3320418AS
- An old VGA Acer AL1512 15"
- A newer DVI Samsung S24B420BW 24"
- Various USB devices