5. Recommendations
5.0 Intel Sockets
LGA-775. A very long-lived socket. It has housed CPUs from the Pentium IV era, through the Pentium Ds and into the Core 2s. Unfortunately, having a LGA-775 socket does not guarantee, compatibility with modern Core 2s, you will have check your motherboard manufacturer's website. Most CPU updates broke comparability with old motherboards; even Conroe Core 2 motherboards are often incompatible with Wolfdales. By all means upgrade your CPU, though, Core 2s are very, very solid performers from the low range to the medium high. This socket is currently EOL, not recommended. Uses mainly dual-channel DDR2.
LGA-1156: A brand-new socket built for new Core i5s and i7s. It provides good performance and value; however, the longevity of the socket has been highly questioned. Buy it for cheep performance now, but do not count on future upgradability. Also, since the CPUs hold the PCI-E controller, it is currently impossible to have a 16X-16X SLi or Crossfire array, which will likely bottleneck high-end graphics solutions well before the CPU performance does. At the moment, conditionally recommended for medium-high cost platforms. Uses dual-channel DDR3, restricted to voltage levels below 1.65V
LGA-1366: A high-performance solution for the most powerful systems. Intel's future Core i9 processors are expected to use this socket. Built for high-end Core i7 systems. Expensive. Recommended for all top-end systems, and mid-end productivity and media editing systems. Uses triple-channel DDR3, requires voltage leves below 1.65V
5.1 AMD Sockets
AM2: An obsolete AMD socket. Build for Athlon 64 and 64 X2 systems. Still provides adequate performance in low-end systems. Often compatible with up to current AMD processors - check your manufacturer's website before you throw out these boards. Not recommended for new systems, but don't necessarily need replacement either. Uses dual-channel DDR2.
AM2+: An intermediary between AM2 and AM3. Guaranteed compatibility with *all* production AMD processors. Provides good performance from the low range to the medium high. One of the overall lowest-cost platforms. Offers excellent value. May not continue to be supported far into the future. Recommended under that condition for low- to mid-cost platforms. Uses dual-channel DDR2.
AM3: AMD's current socket. AMD's future "Bulldozer" CPUs are expected to work with AM3 sockets. Provides good performance and value in low- to medium-high price catagories. Compatible with most production AMD CPUs. CPUs must have a DDR3 memory controller, if they are labeled "AM3", they do. Performs slightly higher than AM2+, but has a slightly higher platform cost. Recommended for low- to medium-high cost platforms. Contrary to what I suggested earlier, this will NOT be compatable with Bulldozer. Do NOT purchase this and expect to upgrade farther than a 1090T.
5.2 CPUs to avoid.
AMD Phenom: Hot and with poor performance. Not recommendable now as the Athlon II X4 brings the quad-core performance to the ~$100 level, with higher clockspeeds and much less heat. Before availability drops too low, however, the 9950 may be a good choice for boards that do NOT support Athlon or Phenom IIs.
Intel Pentium 4 and D series: Hot and with poor performance and reliability. Not recommended under any circumstances to anyone with the ability to drop in an e5200 at the very least. If you have a motherboard that can't support anything else, don't put any more money into that system.
Intel e8X00 Series: The e8400 costs $170, and they go up from there. For reference purposes, the Phenom II 720 costs $120, and the Q8400 costs $170 and they may have lower maximum FPS, but much higher FPS in anything more than dualthreaded, and often higher in dualthreaded applications in a less-than-pristine operating environment. This CPU used to be the "to-have" gaming CPU, but competition from AMD and Intel's own product line make this CPU good for little more than bragging rights.
AMD Phenom II 965 C2 Stepping: Badly overpriced compared to the Core i5 750 and Phenom II 955. Identical silicon to the 955 does not approach justifying the price premium. That the 955 has an unlocked multiplier that can be upped everytime to make performance idential makes this even more outrageous.
Intel Clarkdale i5 line: Intel seems to think it's funny, like a clown, running two separate i5 lines. I jest, but at current prices, stay away from the i5 6XX line. If you want dual-core speed, get yourself a much cheaper i3 or Phenom processor, if you want parallel threading, get yourself a much cheaper Phenom II or a cheaper and faster i5 750.
5.3 Recommended CPUs.
Low-End
AMD Athlon II 250: This CPU is cheap and very fast at stock speeds. For around $60 bucks you can have a CPU that will run almost any game and make for a very snappy operating environment. This CPU runs very "cool 'n' quiet", and runs in a current socket. It overclocks decently, but not like the e5200. Recommended for running at or around stock speeds for a sure thing.
AMD Athlon II 435: This CPU is cheap and quick, and just over $70. It's fast, it OCs a bit, and isn't very warm. Like the rest of the Athlon II line, it runs in Socket AM3, a modern socket. Recommended for gaming or a compromise between gaming and threaded performance.
Intel Pentium Dual-Core e5200: This CPU is very cheap as well, also around $70. It performs poorly at stock speed, but is a formidable OCer. Of course, OCing is a tossup, you will need a decent motherboard and cooling that will handle the overclock, and you could always get a bad CPU. But if you don't, and you probably won't, you will get some of the best value available. Recommended only for big overclockers.
AMD Phenom II 555: This CPU can be had for around $100, and it smokes both the Athlon II and the Pentium Dual-core at stock and OCd. It brings tremendous value to the table, it will run any current game very well, and there is a decent possibility you can unlock disabled cores on a SB710 or 750 motherboard. A good performer at stock and overclocked speeds. NOT recommended for productivity or media editing PCs, this is all about the gaming.
AMD Athlon II X4: Again, an excellent value low-end quadcore. Can be had for around $100. Outperformed by the Q8400, but cheaper than either that or the Phenom II 720. Not an excellent gaming CPU, it has poor performance-per-clock, but four physical cores allow it to excel in heavily multithreaded applications. Not a great overclocker. Recommended for home and work PCs not used for gaming.
Mid-End.
Intel Core i3 530: This CPU can be had for around $120. Games tremendously, and OCs quite well, if not with the best reliability. Beats the Phenom II 555 just well enough to justify the price premium. If you need more threaded performance, consider the Phenom II 720 (before it's phased out), or the Athlon II X4, which performs much better in more parallel universes.
AMD Phenom II 720: This CPU can be had around $120, and performs very well in gaming, and adequately in encoding or productivity tasks. Overclocks generally well, does not unlock consistently. Will run any game, again, not a great productivity unit. Recommended for gaming and all-purpose PCs.
AMD Phenom II 955: A very solid performer. Can be had for $165, or less with good combo deals. Good overclocker, but can be a bit warm as well. Needs its voltage. Excels in gaming at stock and overclocked, performs well in other areas too. Does not perform at the level of the Core i5 at stock, gains some ground back at higher clocks, but still doesn't consistently win, but it's unit and system cost make it very attractive. Recommended for all medium-end systems. For more performance in this class, look to a Core i5 750 for a little extra dough.
Intel Core i5 750/760: An excellent performer. The 750 can be had for under $200; but the 760 if it's less than $10 more. Excellent overclocker, tends to need alot of voltage. Only real drawback is platform limitations, and to a lesser extent, platform cost. CPU cost can be misleading; the price for a Core i5 systemis generally higher than that of a Core 2 or Phenom II system. Quad-threaded and under performance is excellent, but loses badly to the Phenom II X6 and Core i7s once more threads are in play, and concerns have been raised about the longevity of the LGA-1156 platform relative to LGA-1366 and AM3 platforms, possibly valid. Limited to 8X-8X SLi and Crossfire, not much of an issue outside of top-end GPU configurations. If these are issues, get an AM3 or LGA-1366. Under these conditions, recommended for mid-high-end PCs. Note: requires memory with voltage of 1.65V or lower. If you plan to OC heavily, make sure your motherboard doesn't use a Foxconn socket.
AMD Phenom II 1055T: For $200 the cheapest hexa-core processor out now performs admirably for it's price tag. Comepetes with the more expensive i7 860/920 in more multithreaded applications (and shellacks the i5 750 in these cases), but loses quite badly once in less mutithreaded situations. Not a gaming CPU, but a fantastic buy for more productivity-oriented machines. OCing seems good, but I'll update this soon when more results come in. Very strongly recommended for middle-end non-gaming machines.
The High-End.
Intel Core i7 860/920: Here is the big performance - the fastest CPU architecture on the planet. The 920 Can be had for $280, and with a much noticeably more expensive platform cost than the LGA-1156 and AM3 platforms. This architecture has an outrageous performance lead when clock-for-clock, and OCs very high under the right cooling. Be willing to pay a price premium for a D0 stepping processor, which are the best overclockers. The i7 series provides exceptional SLi and Crossfire performance in gaming, and serve all other quad-cores their lunch. Recommended for well-rounded high-end performance for a premium, and the best gaming performance available. The 860 has some mild SLi/Crossfire scaling issues, as it only supports an 8x8 interface, but on top-end current-gen cards, this is a <10% performance loss, and usually <5%. If you plan on Crossfiring HD5XX0s, or SLiing GTX 480s, maybe go with the LGA-1366 platform. If you plan to OC an 860 heavily, don't buy a motherboard with a Foxconn socket.
AMD Phenom II 1090T: A monster CPU. A blunt-force counter to Intel's superior architecture, this is a very large piece of silicon. For $20-$30 more than the cheaper i7s, the 1090T tends to outperform them in multithreaded apps, but usually loses otherwise. Like other Phenoms IIs, it overclocks well, especially with good cooling. Highly recommended for medium- and high-end productivity machines, but pure gamers would be better served with an high-end quad-core.