PSU - Time to upgrade? Recent mods made

Hopefully ya'll can help point me in the right direction. First off, here is my problem. When playing games, my computer will randomly shut down completely. Sitting idle all day and the computer does not shut down, only when I seem to excersize it.

I had not problems before my upgrade but I recently added:
Processor: AMD Athlon 64 X2 5400+ 2.8GHz 2 x 512KB L2 Cache Socket AM2 65W Dual-Core Processor - OEM
Gfx card: ECS N8800GTS-512MX GeForce 8800GTS (G92) 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Retail

I believe it is my power supply that is causing this problem as it is not strong enough to drive these components. I reboot and check my BIOS specs and shows the +12V to be around 11.7V (I know it does not indicate current, but seems a bit low).

Here is my PSU specs:
KY-520ATX Raidmax Triple-Fan 420W ATX12V Power Supply for AMD & P4
Type: ATX
Maximum Power: 420W
PFC: N/A
Input Voltage: 115v - 230v manual switch
Input Frequency Range: 47-63Hz
Input Current: 10/6A
Output: +3.3V@26A, +5V@32A, +12V@13A, -5V@0.5A, -12V@0.8A, +5VSB@2.0A

This is the MOBO I have: AM2 MB - MSI K9N6PGM-F AM2 NVIDIA GeForce 6100 Micro ATX AMD Motherboard


3 Questions:
1 - Will my current power supply work for the 2 upgrades I have listed above? Do I have insufficient power or is my PSU going on the fritz?
2 - Anyone recommend a good supply for my needs (maybe future expansion) for a decent price? $100ish, but I am flexible.
3 - Should I look at other components that may cause my computer to completely crash. I have to turn on my computer again, that is how hard it crashes.

Thanks, I figured as much but wanted to check with the masses. Thanks for the quick response as well. I will look at the links and come back for additional question I am sure!

Thanks again for the response.

Yes you need new power supply before your old one kills something in your system..
Here is the one i would recomend it is a little more that the other suggestion but can not beat PC & Power

Thanks all for the recommendations. I went ahead and got the 650W Corsair. I was overly impressed with the way they packaged it, encased in its own bag, and gave the impression they really paid attention to detail.

I installed it, loaded games and it was rock solid. I was even getting some abnomilies, flashing polygons, etc with my old supply. The 12V is rock solid at 12.17V. Things appear to run pretty smooth as well.

Overall, very impressed and time to load it up! I will have to get a new case and MOBO if I want to add another FX card.

Thank you again all!