will I need to upgrade my PSU w/ addition of TV Tuner card,HDD?

[stevethebrain]

here's a link to my new PC
Newegg.com - Acer Aspire AM3910-U4012 (PT.SDX02.086) Desktop PC Intel Core i3 550(3.20GHz) 6GB DDR3 1TB HDD Capacity Intel HD Graphics Windows 7 Home Premium 64-bit

I plan on adding a full size internal PCI TV tuner card (dual tuner) and a 2nd internal 1TB HDD, possiablly a 60GB SSD for OS.

will the stock OEM 300wat Power supply be addaquite? and is there a way to test it's preformance?

edit I also plan to use my Western digital world book external 1TB HDD for back ups.
?since the WB has it's own power supply (I have to plug it in a AC outlet) will it put any additional strange on the PCs power supply?

Thanks STB

 

[Jake-]

Maybe, 300w is a low amount however this PC hasn't got any power sucking devices in, like a graphics card or water cooler.
To be sure use this eXtreme Power Supply Calculator
Its a PSU calculator, itll tell you what wattage PSU you need.