PC doesn't boot

[l30]

first of all here's my PC configuration :

AMD Phenom II X 965 black edition 3.4 ghz (Stock cooler)
Crosair 4(2X2) GB DDR2 RAM
1TB seagate+1TBWD+500GBWD
AT radeon 5750
1X DVDWriter
CrosairHX850w Modular PSU
____
I was playing darksiders with my CPU and monitor's power cable directly connected to the power board because my voltage was very low.After playing for an hour my PC turned itself off forcefully! and won't start again.I thought because of low voltage.When voltage cam back to normal,I tried again and it didn't start.I thought my PSU is fried.So I bought new PSU (CoolerMaster 850w modular).But PC didn't start with this one too.after trying for couple of hours I connected my 500 watt PSU from my 2nd desktop and PC started!But,when I tried reconnecting the 850w one it didn't start.So, what might be the problem?

 

[Twoboxer]

I don't know what you mean by "with my CPU and monitor's power cable directly connected to the power board".

If I understand you correctly, your third psu - a 500W from PC#2 - successfully booted PC#1. If so, try your Corsair and your Coolermaster in PC#2 . . . when the voltage is OK lol. That will tell you whether they are working PSUs. From what you describe, both of them are bad.

You might install a UPS so that you can protect your PC and shut it down gracefully when the voltage drops.

 

[l30]

Thanks for the reply.
I mean't that voltage was too low to use UPS,my UPS was running on DC and yes,I did connect both of the PSU to PC#2 but that one didn't boot with this PSU,neither with Crosair nor with the CoolerMaster.
But How can both be bad, I bought CM850w one yesterday and I have UPS installed (1100)
Anyways, now I wouldn't be worried to much as long as my PC runs without any problem,right now I am running my PC with 500 watt PSU but it's wire is too short ,so it can't be fit cabinet properly.
Can I run my PC with a 500w(generic) PSU?
I have 3 hard disks connected now (1TB seagate,1TB WD and 500GB WD)
AMD Phenom II X4 965 BE
ATI Radeon HD 5750
Crosair 4GB DDR2

 

[Wamphryi]

I have to say I suspect a connection between your power issues and PSU troubles. If they have been recieving power spikes and or surges then sooner or later they will die. As Twoboxer said its time to invest in a UPS.

 

[l30]

@Wamphryi,I am using an APC 1100 UPS now

 

[Wamphryi]

Its possible both are bad. Unusal but not impossible. As Twoboxer suggested try them in your other PC.

 

[Wamphryi]

@Wamphryi,I am using an APC 1100 UPS now

Sorry Dude I had written it just before your message came up confirming the presence of the UPS

 

[l30]

Its possible both are bad. Unusal but not impossible. As Twoboxer suggested try them in your other PC.

I tried on different PC and didn't work.
Now, what I m more concerned about is getting back to my gaming again lol.
So, now I m planning to buy another PSU.My question is how much power do I need?

 

[Twoboxer]

So far it seems you are having some incredibly bad psu luck.

As far as we know so far: the first one fried, the second is a factory defect (bring it back - long shot, but could be it is incompatible with your psu), and your 500W is doing fine. Yes, 500W is enough to run your system.

Once the UPS goes on DC, you're going to have to shut down before the psu shuts you down.

 

[l30]

Still waiting for a good solution.Right now,running with a 500w generic PSU.but still don't think that those 3 new PSU were all bad.