USB weirdness, devices dropping, display going black

Hello,

I've had this PC for some years now, and I've been having USB issues with it for a few years.

Plugging devices in a specific configuration causes some to underperform or fail. Network adapter drops out, or USB hub stops seeing devices. I actually got the USB hub to solve these problems, because IF the hub is stable, plugging things in and out of it does not cause problems.

It started with a lit keyboard some years ago, where if both the kb and mouse were in the same set of ports they would intermittently turn on and off. Once a stable arrangement is found, there are no issues.

However, plugging things directly into ports sometimes causes the new keyboard light to suddenly go off.

This brings me to the worst of all: whenever I plug certain devices into my card reader's USB port, even as much as touching it, the screen suddenly goes black and PC stops responding, with the monitor saying there is no signal. This happens in both Windows and BIOS so it's not a software issue. I had to tape that port closed to remember to never use it.

The card reader's odd interactions don't end here. Sometimes, I'd say about 1 in 20, when I plug an SD card into the reader, the entire screen completely freezes. Funny enough, the PC still works. The keyboard lights for num lock, scroll etc. respond and the PC can be pinged and its network share is accessible. There is HDD activity too. But I have to hard reset anyway.

At other times, plugging devices in causes the screen to momentarily go black and resume with Windows says the display driver stopped working and recovered.

Faulty wiring is unlikely because a year ago I changed my PC case and had to disconnect everything and reassemble it in the new case, the problem has not gotten better or worse.

By now I am aware that the motherboard has USB issues, but I am looking for recommendations and troubleshooting that don't involve a new motherboard or PSU because I can't afford those.

Thank you.

 

PC: Custom-built desktop.

OS: Windows 7 Ultimate x64 with SP1 and all available Windows Updates.

Motherboard: ASUS P5B-VM SE with latest BIOS 1101

CPU: Intel Q6600 2.4Ghz revision G0

RAM: 4x Kingston HyperX DDR2 2GB (8GB total)

Storage:
Kingston SSDnow V300 (120GB) SATA
Western Digital (320GB) SATA
Western Digital Green (640GB) SATA
Western Digital Blue (1TB) SATA

Removable Storage:
ASUS DVD+/-RW IDE
Manhattan Card Reader w/ 1x USB interface

GPU: AMD Radeon 6850HD 1GB DDR5 256-bit

PSU: ThermalTake SMART 550W Active PFC

Other:
6x Case Fans
USB-connected APC UPS 1100W

USB port usage: 8 out of 9 ports in use(note above post which one is vacant and why)

Overclock: Yes, relatively recent compared to the longstanding problem. FSB-only, from 266 to 300Mhz. No RAM multiplier change. GPU also overclocked by 6% both GPU and VRAM. Again, problem is much older.

 

This is another thing I tried. I booted the PC into BIOS using only the keyboard plugged into USB. The moment I touched the front USB with my tablet's connector, the display went black. I am in the process of purchasing a new card reader since the current one doesn't support SDXC anyway, and hoping that somehow the new one will be more light on the system but I'm not getting my hopes up.