Hi there, So I have upgraded and hacked the system to run mavericks, but have found my system jittery when playing HD video via iTunes. It tends to lag or drop frames so the picture remains static while the sound continues unabated. Just wondering what people would advice for upgrade? The config is as below: 2.66 GHz Dual-Core Intel Xeon 13GB 667 DDR2 FB DIMM ECC-2x512 ATI Radeon 5870 HD Several 7200rpm HDD So does it need more RAM or CPU upgrade the best way to go? If CPU upgrade - does it need to be a 'mac pulled part' or will any processor do? (Was thinking http://www.ebay.co.uk/itm/Apple-Mac...Computing_CPUs_Processors&hash=item232b1c4da0 - but am open to suggestion for what the best thing to use would be - preferably the highest power CPU that would work but I am a little out of my depth about what would be suitable.) Thanks in advance!