|For graphics, SLi is the technology for pairing up two nVidia based video cards to theoretically double the performance. It rarely works out that way though.|
An SLi power supply just means that it's capable of handing the power requirements of two video cards & has the necessary PCI-e power connections for the two cards.
SLi RAM has nothing to do with SLi at all...it really should be called EPP. I've seen it described as either Enhanced Profile Protocol or Enhanced Performance Profiles, not sure which is correct. But basically it refers to additional performance memory settings programmed into the EEPROM chip on the memory module, along side the standard JEDEC memory settings. If the motherboard supports EPP, you can enable it & use the settings, otherwise you have to manually configure the RAM settings (which IMO is what you should do anyway). Basically, EPP makes it easier for people who aren't familiar with configuring their RAM.
Your RAM is probably beyond what is actually necessary for your CPU, unless you plan on overclocking. The Q9300 runs at 1333MHz FSB (333MHz frequency), your RAM runs at either 1333MHz DDR (667MHz freq)/JEDEC or 2000MHz DDR (1000MHz freq)/EPP. That means that with the CPU running at default & the RAM running the JEDEC settings, the CPU:DRAM ratio is 1:2, which is ideal.