Random shutdown after MB/CPU/RAM upgrade on Vista x64

I upgraded my Vista x64 system with new;
1. MB - MSI K9N Neo V3 AM2
2. CPU - AMD A64 X2 5600+ AM2
3. RAM - 4X1GB DDR2 800

I used to have:
1. MB - ASUS A8N32-SLI Deluxe S939
2. CPU - AMD A64 x2 4600+ S939
3. RAM - 2X1GB DDR 400

I'm running it on Chieftec 410W PSU, which according to ASUS PSU calculator is enough. Actually my previous S939 system needed more(400W) power than my new system(350W) according to ASUS PSU calculator, and it ran well. It quite old though. 3 years probably, but it's not making any noise and it isn't running hot. It has a big 12cm fan which is running fine and apparently doing a good job.

After Vista reinstall my system randomly, completely shuts down (like when unplugged from power outlet) 2-5 minutes after booting up. Booting process is actually succesuful. All drivers running.

I checked ;
1. cables and srews. Fine.
2. temeperatre. CPU 25-30C, chipset 30C according to MB BIOS. Constant. Fine
3. RAM. Tested in Vista 2pass memory test. Fine.
4. Uninstalled everything not necessary (only MB, CPU, CPU cooler, 1GB RAM, GPU, mouse and keyboard left) to test and relief PSU. After this it seems it is shutting down even faster than before.

It doens't shutdown in Safe Mode though.

What could it be?
PSU? Or MB? Even maybe faluty CPU?

People tell me it is a PSU, but it is just an easiest thing to say. I don't want to spend a lot of money on new PSU finding out it was something else.

I had the same problem a few months ago, after a week of trying different configurations I replaced the mobo (Asus P5N32-E SLI) and the problem was solved.

This might not be the answer to your problem, as IMHO you should be running at least a 500w PSU, but faults like this are hard to pin down and unless you have lots of spares about, it will usualy cost you to find the fault.

If you have a friend with a spare PSU I would ask if you could borrow it.
If you have no spares start with the cheapest bit of kit you have (PSU) and replace that.
Slowly work your way up until the problem is solved.
You may want to take it to a computer shop to get them to do it as they do have spares and it could save you money in the long run.

Try booting into the bios and leaving the computer running.
If it resets whilein the bios it is a hardware fault as there is no software installed.
Try flashing the bios to the latest stage.

Yes it is easy for people to say the power supply BUT in most cases it is the problem.

Regardless if the power supply is your problem here you should replace it as it's not
good to run a PSU at close to it's max wattage rating and those calculators are not real accurate.

I can recommend the Corsair HX series CORSAIR VX550W 550W Power Supply CMPSU-550VX Power Supply Retail at ZipZoomfly
I have the 550 and the 620.

You can also look at these sources..

jonnyGURU's Personal Website
Official XS Tiered PSU Manufacturer Brand Listing Phase III - XtremeSystems Forums (get Tier 2 or above)

edit: Does your BIOS have readouts for your power supply rails? What is the 12volt rail reading?

I tried that already. It is not shutting down in BIOS nor Safe Mode. At least not within 2 hours.
Unfortunately, there is no one with a computer around here where I live. I just have to go to the nearest town and buy what I need.

Are you getting any blue screens/error codes when it goes?? You can check the reliability monitor (start/search "Reliability Monitor") for a general record of what failed.

But if it's just shutting off and you've verified connections, I'll go with the consensus and point at your PSU. Recommendations?? Stick with a name brand, and buy a good chunk more than you need. PC Power and Cooling make what's generally considered to be the best, but those aren't cheap.

A little old, but: Strong Showing: High-Performance Power Supply Units | Tom's Hardware

A sticky thread from the same site with links to other useful info: http://www.tomshardware.com/forum/24...8-power-supply

get into bios and monitor cpu temps for a while...since you took off the heatsink, im guessing you took off the old thermal paste and put a new coat on it..

It was a bad PSU.
I bought an expensive and fancy 600W PSU, and now everything works.
Thanks for replys.

I bought this new toshiba and it crashes all of the time, out of the clear blue sky.
I have two other relatives having the same problem.
Seems Microsoft would have enough knowledge to put out an os without all of these issues.
I am selling this toshiba/vista and giving up on microsoft for good.
The commercials are right on the money.
Apple wins hands down
Microsoft can't even produce an operating os these days
Worst mistake toshiba could make was to align themselves with microsoft.
How pathetic!