Do I need more power? or a new motherboard? HELP!

OK here is the deal I hope you guys can help me out.

My system specs are as follows :

ABIT BH6/PIII-850MHZ/384MB PC100 RAM
Hercules G-FORCE II ULTRA 64MB DDR
Adaptec 29160 Ultra-160/ 18.4 Seagate Cheetah 15,000rpm
Plextor UltraPlexWide 40X/ Plextor 12x4x32 CDRW
Linksys 10/100 Eithernet Card
Soundblaster Live Value

Lots of fans, full height case, with power-man 300-watt power supply.

The PROBLEM , read carefully. The machine worked fine when I had a Adaptec AHA-2940U2W and a 10,000 rpm Ultra-2 Cheetah hard drive. Recently I sold the controller and hard drive, and upgraded to a 15,000rpm Cheetah drive and a new Adaptec 29160 controller to go with it.

Every since I added new 15,000rpm drive and new 29160 controller I have been having a problem I cannot figure out.

Evertime I go into my favorite game Half-Life my system locks up. I get total BLACK screen, and it looks as if the monitor was turned off. I have to HARD RESET to get back to windows.

When in windows everthing is fine, but whenever I switch into a OpenGL game, my system locks. Now I never had this problem when I had the old Ultra-2 10,000 rpm cheetah hard drive, and the old adaptec AHA-2940U2W controller.

I tryed re-installing the OS lots of times, and still same problems.

NOW HERE IS THE WEIRD PART!! When I take out the G-FORCE II ULTRA and replace it with my older Viper 770 Ultra "TNT-2 ULTRA" my system runs fine. I can play all my games and never have any problems.

DO YOU THINK THE NEWER HARD DRIVE AND CONTROLLER ARE TAKING MORE POWER, AND BECAUSE I HAVE A CHEAPO 300 WATT POWER SUPPLY I AM RUNNING OUT OF POWER? WHAT ELSE COULD IT BE?

If I pop in a good name brand 400 watt power supply do you think I will be OK?? Or do you think I might have some sort of motherboard problem? Remember the G-FORCE II ULTRA WORKED FINE IN THIS BOARD, UNTIL I REPLACED THE HARD DRIVE WITH A NEWER FASTER ONE, AND REPLACED THE HARD DRIVE CONTROLLER.

Please give me your opinion on this! ALSO!! I tryed the video card in a one of those new Compaq computers and it worked fine, so I don't think it was the card, although the damm card runs super hot even when the case is open.

Sounds like it might be power related.

Disconnect all of the case fans and the CD-RW and run the system with the case open so the system remains cool. Also, underclock the video card. This will also reduce power. See if your games are stable for long periods of time.

If they are stable at this point your problem is either power-related or it is heat-related.

To determine which it is, return everything to normal, reconnecting everything you disconnected. However, leave the case open and aim a nice house fan at the open space. You should get plenty of cooling. If the system begins to fail again then your problem is power related. If still works stable then the problem is heat related (probably an overheated video card).

If it turns out to be a lack of power, I too recommend the Enermax EG451P-VE for your situation (unless you would like the overkill of the EG651P-VE, 650 watt PSU ).