Posted 29 June 2008 - 02:13 PM
You will want to use the PCI-E X16 slot as most all of the current graphic cards use this. With only the one PCI-E X16 slot you will only be able to use one graphics card.
I googled their warranty last night, and couldn't find anything definitive in regards to voiding your warranty by opening the case. The warranty does state that if you have a problem with any components that you have installed that weren't purchased from them they wouldn't honor the warranty. I would suggest calling Acer and asking them what their policy is on upgrades, their contact phone number for the U.S. is 1-800-571-2237.
The good news about the PSU is that it is a ATX form factor which means that you can purchase any number of PSU from places like Newegg. When you decide on which graphics card you wish to use, look to see what the power requirements are for it, and then give it another 50W for future additions. Most graphic cards now are becoming more efficient and a PSU of 350W without SLI or cross fire, and 400 with SLI or cross fire.
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