SFFPC wiki

You probably to this page from the Beginner's FAQ page and you are ready to get into the next step, planning everything. This is important to make sure all your parts fit in the end and the build works. Everything needs to be checked : hardware compatibility, size clearance, availability, …. Here are a few tips to get through it.

There are two main methods to make a small build :

1. Build in a specific case : you are dead set on a case you like. You want to build in it no matter what. This means you will have to very carefully inspect the case's specifications and make sure the parts you make fit in there. This method is mostly about physical clearance and dimensions. One downside is some case can prevent you from using the biggest hardware, which means you may not be able to get the best parts you could otherwise afford. It is a tradeoff.
2. Build around specific parts : You picked parts because they give you the performance you need. Now you need to find the rest of the build to go around, and find a case that is big (or small) enough to fit it all. This method has the advantage of focusing on performance first. However, you might end up with a “big” sff case to fit it all depending how powerful your components are.

Both methods are valid, and it depends on you to pick one.

The rules here are pretty much the same as all computers. A more powerful CPU will give better peformance, but can also lead to increase power consumption and heat output. This can impact the PSU choice and more importantly Cooler choice. As recent high end CPUs have been creating more heat, cooling them in small cases is a bigger challenge.

There are a few interesting notes however :

• If you are gaming, there are diminishing returns on the number of CPU cores. Games do not scale much with more cores past 8 cores/16 threads as a general rule. This means the performance difference between 8 and 16 cores will be minimal and often not worth the price.
• Gaming is not necessarily a very heavy load on the CPU. This means even if you have a 14900K or a 7950X, the CPU may not be used at 100% and may not be that hard to cool.
• Heat is mostly related to power draw. 80w of load is easier to cool than 150w, regardless of what the CPUs are (at least in theory, there are other factors like thermal compound and IHS but those will not make much difference for the average build).

CPUs have to be cooled to avoid overheating. The two main choices are air coolers (fans blowing air onto a heatsink) or water coolers (fans blowing air onto a heatsink but the heat has been transported from the CPU to the heatsink with water).

• Water coolers have more thermal headrooms than air coolers. They are more suited for bigger, hotter CPUs. They require dedicated mounting points for the radiator. They can often make for more space efficient cases.
• AIO (All-In-One) water coolers require no maintenance whatsoever. They are closed loops and the user is not expected to open it or maintain it. Some vendors have started offering “refillable” AIOs but those are an exception.
• The risks of water leaking is now almost non-existent. It is very, very rare for an AIO to leak.
• Air coolers provide more simplicity : less moving parts, no pumps, even less maintenance than AIOs, and naturally fit on the socket given enough clearance.

There is not really a “better solution”. Some prefer AIOs, some prefer air coolers. Both are valid and perfectly good options as long as they are suited for the entire build.

We are currently past the early DDR5 products. As of AM5 and next gen Intel sockets, DDR4 is no longer compatible. DDR5 has been out for a bit now and we are seeing kits reach past 7000mhz on XMP without too much trouble with recent boards and CPUs. There are specifics to keep in mind about QVL, frequencies, and more.

Be mindful of the height of your ram modules as they could conflict with some low profile coolers. Double check specifications to make sure it works.

Storage all depends on your needs. Some need more, some can work with less. The only note is that most SFFPC users rely on M2 drives for space efficiency as many case no longer fit 3,5“ hard drives and even 2.5” is getting rare. Also M2 don't rely on extra power cables, which is great for cable management.

Motherboards will mostly be Mini-ITX as it is the smallest form factor that is “easy” to obtain. You will need to check the CPU compatibility and RAM QVL (optional) to make sure everything works. Note that while Mini-ITX boards have only 2 ram slots, modern boards can easily fit 2x32GB kits, and with DDR5, 2x64GB should be doable, although at lower frequencies for stability. Bios compatibility is also important, especially on AM4. Thankfully vendors have CPU compatibility pages with the bios versions needed to make each CPU work each motherboard.

Be mindful of clearance with M2 and VRM heatsinks for CPU coolers. This is usually a non-issue for AIO watercoolers, but some air coolers can conflit and not fit with boards, despite being “socket compatible”.

During the past 3-4 years, we've seen interesting (or not) things about GPUs releasing. They have gone bigger. Especially with the RTX 4000 series. Some are now 4 slots thick and cannot fit even in some large cases. We also have Intel GPUs now, so this is neat. Power consumption has also gone up, and PSUs had to change too (more on that later).

GPUs are still often a good chunk of the budget. It can easily be a third of even half the total cost depending the model. The most important part is to check if it fits in the case you pick.

Note : the actual GPUs are made by AMD, Intel and Nvidia. They then sell the chips to partners like Asus, Msi, Gigabyte, Sapphire, Asrock and more that will then put it on a PCB and sell it under their brands. But an RTX 4090 is almost always an RTX 4090, regardless of who sells it. The only differences are the cooling solution, and sometimes a slight factory overclock. Nothing to make more than 5% perforance difference out of the box however.

Some cases can use PCIe risers to connect GPUs to the motherboard's PCIe slot. This can be an issue because some risers are rated for a PCIe generation (like PCIe gen 3.0 or 4.0) but because risers are essentially a cable, it is not smart and will not tell the motherboard about it.

As a result, if your motherboard and GPU can work at PCIe gen 4.0, but not your riser, you may end up in a situation where things don't work as intended.

A lot of builds rely on SFX power supplies, which is a smaller form factor than the traditionnal ATX used in all larger towers. Because they are smaller, they user to be lower capacity. With time, we now have 750w and 850w SFX units available, which should be enough to cover almost every build with a single GPU for gaming.

SFX-L is a variant that is sometimes compatible. The only difference with SFX is the depth. This often makes cable management harder so people like to stick to “true” SFX.

Some rare cases will fit ATX, some other will require other niche PSUs like FLEXATX, pico-psus, or non-standard ones.

This section should be the whole wiki, so we cannot summarize it here.

Any respectable vendor that is even remotely serious about their business will have a specification page for their products. This include the dimensions, technical data, and specifics that you need to be aware off. You however, are expected to check components size against clearance by yourself. This is a very important step to make sure you can even make the build possible.

When finding conflicting information, the information from the vendor and its specification page prevails. Always look for specs at the source. Unless third party reviews have proved and demonstrated that it works otherwise (very rare).

Sometimes, the community can make things work despite specifications indicating it doesn't. A good example of this is users fitting the Noctua L12S in the Louqe Ghost S1 by bending it a bit. As the case allows for 66mm air coolers while the L12S is 70mm tall. This is worth considering but is more or less at your own risk. In this example, Noctua or Louqe will not be responsible if anything goes wrong in the bending of the cooler.

Once you planned everything, and all is compatible and fits, you can proceed to order the parts and start building. If you are not sure, feel free to ask the community for help and/or validation on your build.

The last thing to plan for building, is time. It is recommanded for people to take some time dedicated to the building. a few hours to an entire day is not unreasonnable, especially if something ends up not working as intended. Make sure you get a nice saturday afternoon for your build, a nice philips screw driver, and take the time to read the manuals. Really. It does help a lot.