What could be causing this?

[UltraInfinity]

PC crashes and sometimes wont POST help?

ok so I have these two rc helicopters that charge of the usb ports of my computer. I switched on the power to my pc on the wall but didnt press the actual power button as I didnt actually want to switch it on just power up the usb so I could charge the two helicopters. I then decided to boot up my computer a while later and pressed the power button but it didnt boot up. The fans came on 100%, and the hdd light for a few seconds and then went out. The actual power light next to the hdd access light was also out but the fans were still on. The screen was blank and the motherboard LED display had - - displayed I pressed the reset button and it did the same several times: Fans 100% hdd & pwr light out.
Eventually it came on and gave me a message in bios saying that the boot manager was missing/corrupt so i restarted and it eventually worked fine booting into windows normally with no problem.
But thats not all, most times I boot up now first time in the day it crashes. It started off crashing loading windows and would sometimes fail to even post like before with the lights out and fans on 100%. Then somertimes I'd manage to log onto windows and a few minutes later it would either crash with a black screen and restart ok or give the BSOD and then restart. It seems to work fine after crashing a few times and restarting and will stay on without a problem for hours.
But today I came to switch it on and it wouldn't post, no beeps but a power light, black screen, and the fans where on but not on at 100%. So i pressed the reset button and I heard the hdd reboot but nothing else did, as ussualy the fans on the GPU go to 100% as the settings in bios havent tacken effect, so I had to hold in the power button to get it to turn off, and it then started up fine
I've also had it crash and restart with a message in bios saying system in safe mode and it then be fine.
I've tried scanning the hdd for errors, testing the memory, resetting and clearing the cache on the mb using the jumpers and repairing windows. All of witch did nothing
It's been working fine until I charged those two helicopters which I've charged numerous times since it messed up but with the pc actually turned on and not just on at the mains. It's not overclocked and temps are fine and the rc heli's have really small lipo batteries (3.7v) so charging shouldnt use too much power.

Does anyone have any ideas as to what it could be? I'm unsure if it's something to do with windows but if it was why would it fail to post?
I have a theory that the helicopters could have pulled two much current with the pc off and fried part of the mb or psu maybe a capacitor or something? but surely the same power is at the usb's whether the main computer is on or off?

These are my pc specs:

Windows Vista Home Premium service pack 2 32-bit
Processor: Intel core 2 Duo E6700 (Conroe) 2.66Ghz
Motherboard: EVGA Nvidia nforce 680i SLI
Graphics: ATI Radeon HIS HD 4890 1gb GDDR5 ram (Pretty new less than a year old as my old nvidia 8800GTS 640mb broke so dont think this would cause issues)
Ram: 2x 1gb OCZ DDR2 PC2-6400 Gold GX XTC Dual Channel 800mhz
PSU: hec 550TD PTE 550 watt

Thanks for any help or info you can provide

 

[wilko49]

Windows issues wouldn't cause POST failures.

It is possible, although I suspect unlikely, that you have overloaded the 5V stand-by - 5VSB is the power provided on the 5V rail while the computer is off, and is usually 1A or less - you should find this number on the PSU sticker. If you still have the helicopters' packaging/insttructions, they may say the current draw.

 

[Shayper]

^^ this

I can imagine RC items would draw quite a bit of power while charging, I'm always a bit worried by this sort of stuff with my PC, so I never even charger iPhone when the pc is off

 

[Hector]

What mAh are those 3.7v lipo's and do they show a 'c' rating?? Mine are 130mAh which are charged at 1c, that works out to be just 0.13A..

Math: (mAh / 1000) * #c == A

(2000mAh / 1000) = 2 * 1c == 2A
(2000mAh / 1000) = 2 * 2c == 4A

What RC Heli is it, Eflite?

 

[pcAnywhere]

I have a similar issue when I boot with my Kindle attached to the computer. I believe a number of USB2 peripherals draw (or try to draw more) than the USB2 specs.

Not a real issue, just use a dedicated 13amp to USB plug to charge high-draw bits

 

[Vince]

I get similar if I plug my HTC mobile into my laptop before I power it up. I have to wait for post and then plug the phone in or the laptop will fail to post completely, regardless of what settings I use in bios.

If its not because of a 3d party device being plugged in and the pc getting confised then I would do the following:

1: Run hd tune to check for errors... is the disk getting spin up errors or failing to reach its speed.

2: Check PSU and cables to the drive.

 

[UltraInfinity]

I looked at my psu and it has a 5vsb of 2 amps so theres definately enough power there to charge two helicopters easily. The batteries for the helis are only 180mah and their chargeable of the handcotroller using 4AA batteries so I guess a really small amount of current needed.
I've had a few more problems with it too today it started fine and then crashed after a few hours and it took me atleast 10 attempts at restarting it to get it booting up. It also beeped and gave error codes of C1, 75 and 41. Also with one attempt it tried loading windows without the hdd activity light on :s and also gave me errors codes in bios saying: Bios Rom Checksum error and after resetting the jumpers on the mb to clear the cache I got CMOS checksum error twice, and on one occasion it froze in BIOS. The fans have also being doing the same thing staying fixed at 100% with -- on the mb and the reset button not working after it's crashed. So anyone else with any other ideas or ways to rule out the mb?