Saturday, August 13, 2011

Motherboards & CPUs: The Electrified Heart of your PC

08-18-2012: A lot of this information is still useful in a general capacity, but much of it is somewhat outdated.  You can find a more recent version of the post here.

Motherboards and CPUs are system defining components, so be prepared to spend some time and effort on deciding the right combination for your purposes.  They dictate your upgrade paths, your overclocking possibilities, they contribute hugely to the performance of your system, and they're central to a number of other decisions you'll make as you build a PC.


Choosing the right motherboard can help you build a well-balanced, upgradeable system with features aplenty.  The wrong motherboard can lead to copious RMAs and wasted time and effort.  Below you'll find information and recommendations to take some of the guesswork out of choosing the right board for you.

So what stuff matters in a motherboard?

  • Form Factor:  Be aware of the motherboard form factor, you don't want to end up with a motherboard that won't fit in your case.
  • SLI/Crossfire Capability:  This generally comes at a price premium, but if multiple GPUs are in your future (or present) it's worth the money.  However, if you are definitely only going single card, and don't envision yourself ever using multiple GPUs, don't pay the premium.  The basic requirement for SLI is 2 physical PCI-E x16 slots, which run at least at x8/x8 when both are populated.  Crossfire can run with a card in a x4 lane, but performance is compromised and I wouldn't recommend that, x8/x8 as a minimum is your best bet.  Higher end motherboards (or motherboards on higher end sockets) might support multiple x16 slots running at the full x16.  Currently that's limited to higher end AM3/AM3+ boards, X58 boards, and P55/P67/Z68 boards with the NF200 chip.  For 2-way SLI/Crossfire, x8/x8 is enough bandwidth to avoid bottlenecking all but the highest of high-end cards, and even then performance loss is relatively miniscule.
  • VRMs:  The VRM system in your motherboard is a series of small transistors that function as transformers, taking the +12V power from your PSU and sending it to the CPU, GPU and motherboard components in the correct voltages for those parts.  When you see things like "12+2 power phases" being tossed about, they're referring to the number of VRM transformers (in this case, 12 for CPU power and 2 for GPU power).  More power phases means lower individual loads on each transformer, which makes for a more stable experience, especially when overclocking.  Fewer VRMs, or VRMs of inferior quality, can mean catastrophic damage to the motherboard and potentially other components if you push things too far. 
  • Physical Layout:  The advent of all double slot GPUs all the time has made the layout of the board, in particular the PCI-E slots, of even greater importance than before.  For SLI/Crossfire capable motherboards, you want at least 1 additional expansion slot's worth of space between PCI-E x16 slots to accommodate 2-slot coolers.  For motherboards supporting only 2 GPUs, I'd recommend looking for 2 slot's worth of space, to give the top card room to breath.  SATA ports should either be of the 90 degree variety (so parallel to the PCB) or placed to ensure they won't be covered by longer graphics cards.  Front panel, audio, and USB headers should located on the edge of the board, away from potential conflict with expansion cards.  Along the bottom edge is usually best.  Keep an eye on CPU socket positioning relative to DIMM slots and motherboard heatsinks.  It's tough to avoid DIMM slot conflicts, but most motherboard manufacturers are very good about making certain their motherboard heatsinks don't interfere with aftermarket CPU coolers.
  • Features:  This is more nebulous, because what constitutes an acceptable set of features is entirely up to the builder's discretion.  Make sure you're buying a board that has all the ports and additional bells and whistles that you desire.  Some boards come with automatic hardware/software assisted overclocking options, for example.  Do your research here, and choose a board that gives you what you want.

What motherboard brands are worth checking out?

  • ASUS - ASUS is currently my favorite motherboard manufacturer.  They usually have some of, if not the, best VRM setups around, and their boards are usually feature-packed with good layouts.  They tend to keep their board lineup relatively simple, which does help prevent confusion.
  • Gigabyte - Gigabyte has a reputation for reliability, which I can anecdotally confirm based on my Gigabyte X58 board.  Their high end and mid-range boards usually come with solid VRMs, though their lower end offerings can be stingy in that area.  Gigabyte generally has solid layouts (with a few questionable calls, like on front panel audio header placement).  Their board lineup can be a maze of secondary designations and extremely similar model numbers (UD3 vs. UD3R for example), and they have not yet moved to UEFI based BIOS.  Many of their Z68 boards also don't support the GPU virtualization technology that makes the switchable graphics for that platform possible  (this shortcoming has been largely addressed by a new wave of Z68XP boards with the Virtu chip onboard).
  • MSI - MSI is my least favorite of the "Big 3" motherboard makers.  Their AM3 lineup was notorious for poor VRMs, even the boards that had sufficient power phases endured engineering/manufacturing defects that could cause VRMs to die in a fire.  Literally.  MSI's layouts for Sandy Bridge have been the worst of the Big 3, with front panel headers and vertical SATA ports placed directly under areas where a second GPU would rest.  In general, their motherboards don't seem as well built or as well designed as competitor's boards in the same price range.  With the TDP and power reqs of Sandy Bridge being so low, and the quality of the VRMs being (hopefully) fairly high, most 115 MSI motherboards aren't likely to be genuine liabilities, but generally I think your money is better spent elsewhere.
  • ASRock - ASRock sprang out of ASUS spinning off a company specifically to target budget-conscious consumers, and as such ASRock is often (though perhaps unfairly) lumped in with companies like Biostar.  Their 1155 offerings contradict that impression, though, with generous VRMs, good layouts and accessory bundles, not to mention their aggressive pricing.[/LIST]

As you'll find in the Processors section, my current opinion is that Intel's 1155 socket is the best option available for all but the most restricted of budgets. 1155 boards come in a few flavors, but the ones suitable for overclocking and SLI/Crossfire usage are either P67 based, or Z68 based. Z68 includes a few additional features on top of those included in P67 boards. Z68 allows for SSD caching, which is useful for those who have a small SSD (usually around 30ish GB) that they'd like to use as a cache. This will improve disk performance and general system responsiveness, though not as much as having an SSD as your boot drive will, so it's of utility only for those with an SSD that is too small to use as a boot drive. Z68 also includes support for using the built-in GPU of Sandy Bridge processors to accelerate video encoding/transcoding. Unfortunately, while there are significant speed gains available using this process, very few transcoding/encoding applications support this at the moment. Z68 boards with the Virtu chip also support using the integrated GPU during low load situations (at desktop, for basic video playback, etc.) in order to reduce power consumption. All in all, Z68 is of relatively little utility, especially if you don't have an SSD or don't need to use one for cache. P67 generally has a price advantage, and the feature sets are so similar that I don't see much reason to pay more. Just for the sake of completeness, though, Z68 boards are included with the P67 recommendations below.

$150 - ASRock P67 Extreme4 Gen3
$180 - ASUS P8P67 Pro
$190 - Gigabyte P67 UD4

$175 - ASRock Z68 Extreme4
$190 - ASUS P8Z68-V Gen3
$180 - Gigabyte Z68XP-UD3P

Options on the low and high end:  For those building with non-K CPUs, fewer VRMs and/or less effective VRM cooling is less of an issue, as there is no overclocking to stress them beyond normal levels.  With that in mind, a solid H67/H61 board is a good bet.  For those looking for very high-end boards (perhaps with support for more than 2 GPUs, or multiple x16 lanes) please ask in the thread.  There are several different offerings, and your particular feature needs and case selection will be important in determining what board is best for you.


Compared to motherboards, where layout, build quality and feature-set are the primary concerns, CPUs are a numbers game.  Synthetic and real-world benchmarks will tell the story of a proc's prowess, so benchmarks and reviews are your independent research pals.  Right now the best processors at reasonable budget levels are Intel's Sandy Bridge processors.  They are faster, clock for clock, than previous Intel and current AMD offerings, and are relatively budget friendly.

The current recommendations:

Intel Core i3-2120 - $127.00: Suitable for budget levels ~$600.  This is a really solid dual core (with HT) that will hold up its end in all arenas.  It's not going to match a real quad-core in heavily threaded apps, but it's not going to be holding your GPU back.

Intel Core i5-2400 - $190.00: Suitable for budget levels ~$800.  The 2400 isn't vastly cheaper than the 2500K, but you can run a cheaper H67 board with it and not lament the loss of overclocking potential, so that helps keep costs down.  Despite its overclocking limitations, it's a great quad-core.

Intel Core i5-2500K - $230.00: Suitable for budget levels ~$1000 and up.  The 2500K doesn't give you Hyper Threading or do your homework, but that's just about the only stuff it won't do.  It's hugely powerful, hugely overclockable, and at $220.00, remarkably affordable.

Options on the low and high end: For really low budget options, I recommend asking in the thread. On the high end, there are the i7-2600/2600K, or the i7-2700/2700K (essentially a 2600/2600K with slightly higher stock clocks). The basic differences between the 2500K and the 2600K are a marginal stock clockspeed and cache advantage on the 2600K's part, and the 2600K has Hyper-Threading. If you do a lot of heavily threaded workloads, like high-end photo/movie editing or graphic design, the 2600K might justify it's $100 price premium over the 2500K. But if you're just an amateur Photoshop enthusiast while you aren't gaming, stick with the 2500K, it's more than enough CPU to handle the vast majority of tasks.

The other option on the high end is to switch Intel's ridiculously overpowered and overpriced LGA2011 platform and use a Sandy Bridge E processor. As I said in this blog post, I don't see any compelling reason for the majority of users to want the kind of horsepower (and expense) that goes along with Sandy Bridge E, but if you're a nutjob for whom price is no object, or a professional who could genuinely use that much horsepower, it is an option.

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