Re: Upgrading Core2Quad to Corei7, running gtx 275 SLI
You will gain FPS (mileage will vary depending on the game, some games are more CPU-dependent than others), but if you already were getting solid framerates with your old system, will you really notice the FPS increase? Since your video cards are the same, running in heavily GPU stressing conditions (high amounts of anti-aliasing, very high resolutions) won't really be affected by the CPU upgrade.
If you are upgrading for other reasons as well (faster video encoding, triple channel memory, future upgrade possibilities e.g. Core i9), I would say by all means go for it, but to upgrade from what you have for pure gaming purposes might be a bit more iffy.
Intel Core i7 3930K | Asus X79 Sabertooth | 4x4 GB G.Skill RipJaw PC3-12800 | 2x EVGA NVIDIA GTX TITAN Signature 6GB SLI | OCZ Vertex 3 240GB SSD | 2x500 GB Seagate Barracuda RAID 0 | LG BD-ROM | Cyber Acoustics CA3001WB 2.1 Speakers | SeaSonic 1250W PSU | 3x Acer GD235HZ 23.6in 120Hz | Silverstone Fortress FT02 | Windows 8 Pro x64 | NVIDIA 3DVision SURROUND
Intel Core i7 2600K | Gigabyte Z68X-UD3H | 2x4 GB G.Skill Ripjaw PC3-12800 | XFX AMD R9 290X 4GB | Intel X-25M G2 160GB SSD | 2x250GB RAID 0 | Samsung BD-ROM | ABS SL 1050W PSU | Toshiba 42" REGZA 1080p HDTV | Antec 900 ATX | Windows 8 Pro x64
Sailor Jupiter (HTPC):
Intel Pentium Dual-Core E5200 | ZOTAC Geforce 9300 | 2x2 GB OCZ Fatal1ty PC2-8500 | WD 1TB | Hitachi 2TB External | MediaSonic HFR2-SU3S2 4x3TB Seagate Barracuda RAID 1+0 | LG Blu-Ray/HD DVD-ROM | FSP 150W PSU | Toshiba 42" REGZA 1080p HDTV | Foxconn RS233 mini-ITX | Windows 7 Pro x86