Cons: Not a "true" quad-core. Won't be setting any speed records
AMD FX-4100 Quad-Core Processor
ASUS DRW-24B1ST DVD Burner
Cooler Master GX-450 Power Supply
G.SKILL Ripjaws X Series 16GB DDR3 1600
Gigabyte GA-970A-D3 Motherboard
MSI Radeon HD 6450 1GB Video Card
Rosewill Challenger Gaming Case
Rosewill 40-in-1 Internal Card Reader
Samsung Spinpoint F4 EcoGreen 2TB Hard Drive
Zalman N Series 2.5" Solid-State Drive
This was a $500 budget PC build where the goal was to make it remain a viable everyday system for the next few years. It wasn't going to be used for much in the way of gaming, but it was going to run 24/7 and get quite a workout with other applications. The main steps were to grab a lot of memory and a quad-core processor that ran at a decent speed, and the AMD FX-4100 seemed to fit the bill nicely. Not only does it run stock at 3.6GHz, but it the turbo mode would automatically bump it to 3.8GHz when it wasn't utilizing all of the processor cores.
AMD's FX-4100 is a quad-core processor, but not in the strictest sense of the word. Instead of four physical cores, the processor has two physical "modules" that each contain two arithmetic logic units and two address generation units. Each module contains 2MB of L2 cache and there is a further 8MB of L3 cache shared between them. It has support for normal instruction set extensions such as MMX, SSE and 3DNow!; in addition it has support for newer extensions like AVX, SSE4.1, SSE4.2, AES, CLMUL, XOP, FMA4 and CVT16.
The "Bulldozer"-based FX-4100 is manufactured using a 32nm High-K Metal-Gate silicon-on-insulator process, and has a thermal design power of 95W. It has native support for DDR3 memory as fast as 1866MHz and features Hyper Transport v3.1. It uses the 942-pin Socket AM3+ CPU socket, which is also backwards compatible with AM3 processors like the Athlon II and Phenom II. Some AM3 motherboards may support the new AM3+ socket wit ha BIOS update if the manufacturer decides to implement it, but it's not officially supported by AMD so your mileage may vary.
The processor cost $95 with a promo code from Newegg, which wasn't too bad. I could have used an FX-4170 for about $25 more, but I decided against that for one main reason. While the FX-4170 is faster (4.2GHz, 4.3GHz Turbo), it's only because of an increased multiplier. Since the FX-4100 has an unlocked multiplier, you can just pop into the system BIOS and increase it yourself to get the speed benefit for the lower price. A quick bump from 3.6GHz to 4.2GHz in the BIOS takes about 15 seconds to change the multiplier from 18x to 21x, and it runs perfectly with the stock heatsink and fan using stock voltage (at least for me -- due to subtle differences, your mileage may vary).
For about $30 we could have jumped to the FX-6100, which is a six-core processor that runs at 3.3GHz. Unfortunately, most of the applications being used on the system wouldn't benefit much (if at all) from having six cores instead of four. On top of that, the lower clock speed would be detrimental and it would be a slower processor overall for what it was going to be used for. Skipping this one was a no-brainer. The FX-6200 seemed to be about the next "upgrade", with a six-core processor clocked at 3.8GHz (4.1GHz Turbo). It did cost an extra $60 or so though, and the only real upgrade part would be the two extra cores that wouldn't be utilized very well in this system.
As for Intel processors, the i3-2100 is comparable to the FX-4100 for the most part -- but it would have cost an extra $25 as well. The i5-2500 would be a big upgrade over the FX-4100, but it was more than double the price. Since this was a budget build, we decided that the FX-4100 seemed to hit the sweet spot of value for cost while still fitting into the overall system budget. Due to the way Windows 7 schedules tasks for processors, the dual "module" design isn't as effective as it could be. Installing a couple of hotfixes from Microsoft will help to mitigate some of this performance degradation (KB2645594 and KB2646060). Windows 8 has already addressed these issues and has further scheduling improvements to help even more.
Installation was easy; line up the arrow on the processor with the arrow on the CPU socket, gently place the processor in the socket and then pull the socket lever down to hold it in place. The heatsink and fan installed cleanly too; we just used the pre-applied thermal pad for this build. Set the heatsink on the processor, hook one clip over one side and the other clip over the other side. Make sure it's pretty straight, and pull the retaining lever back. Not really much to it.
Since this system was going to be used more for applications than for gaming, we decided to pair this processor with 16GB of DDR3-1600 RAM. We also installed an inexpensive ($15) video card for good measure, as this provided some additional video memory, processing and an HDMI output. The GA-970A-D3 motherboard was decently priced at $80 and provided USB 3.0 support, four memory slots, six SATA 6.0GB/s ports and plenty of expansion slots for future use. The goal here was to make this PC reliably and realistically last for at least 5 years for moderate to heavy application usage without having to worry about it being totally obsolete and useless.
Overall this is a great budget processor, regardless of the application. If you have more money to spend, by all means pick up an i5-2500k or something, otherwise the FX-4100 is a safe bet that has decent performance for a really good price. The fact that it has a lot of overclocking potential is just icing on the cake that will give you even more bang for the buck.
At stock speeds this processor achieved a Windows Experience Index rating of 7.2. You can hear the stock fan but it's not too loud, and it keeps the CPU at about 33ºC at idle and up to 51ºC while stress testing with Prime95. I realistically don't see any reason for more processor power than this for this computer in the foreseeable future, so this was a great choice for the processor; it runs everything thrown at it with no trouble. I took the liberty of running a few benchmarks at stock 3.6GHz speeds; the results are below.
SiSoft Sandra Lite 2012.SP5a
Aggregate Native Performance: 39.14 GOPS
Dhrystone Integer Native SSE4.2: 47.77 GIPS
Whetstone Double Native SSE3: 32 GFLOPS
Aggregate Multi-Media Native Performance: 107.92 MPix/s
Multi-Media Integer Native x16 AVX: 127.86 MPix/s
Multi-Media Float Native x16 FMA4: 91.08 MPix/s
Multi-Media Double Native x8 FMA4: 49.47 MPix/s
Multi-Media Float/Double Native x8 FMA4: 67.12 MPix/s
Cryptographic Bandwidth: 1.63 GB/s
Encryption/Decryption Bandwidth AES256-ECB AES: 4 GB/s
Hashing Bandwidth SHA2-256 AVX: 679 MB/s
Inter-Core Bandwidth: 7 GB/s
Inter-Core Latency: 118.3 ns
ALU Power Efficiency: 10.12 GIPS
Power Efficiency: 5.30
PassMark PerformanceTest 7.0
CPU Mark: 4392.9
Integer Math: 840.2
Floating Point Math: 2751.1
Find Prime Numbers: 1182.5
String Sorting: 3391.3
Hyper PI 0.99b
Best Time: 27.487s
Worst Time: 27.862s