There are really only two high-dexterity tasks in building a modern PC: carefully placing the CPU in its socket and connecting up the case to the motherboard.

The former is actually easy: there will be a conspicuous triangle on the CPU which matches a triangle on the socket, and the CPU will, upon being aligned, fall right in to the socket.

The latter is usually underdocumented and requires peering at tiny jumper pins on the motherboard and matching them to slightly differently labelled pins from the case.

Building a system that way offers a powerful feeling of accomplishment.

Local PC stores which seem to have now all evaporated, rather to my surprise.

Try College Street, between Spadina and Bathurst. :)

At least over here (Germany) there are several online retailers that offer to assemble the parts you pick out for a modest fee. I've heard the same from acquaintances in the US, so I'd be surprised if Canadian retailers wouldn't do the same.

If the colleagues can't name a place, there's another source of info: students. There's bound to be local groups and clubs that are into PCs and hardware. Gamers are a good source since they usually shun off-the-shelf hardware.

It might pay off to check either student message boards if such a thing is part of the university's offers, or local meet-ups.

You can get expert compatibility info and generally accurate (it may miss 1-day specials and occasionally otherwise be a day or so out of date) on http://ca.pcpartpicker.com/, which also has a few curated build guides and several examples of completed systems. You can sometimes get a cash discount at bricks and mortar versions of the major online retailers in the GTA (dunno about downtown presence).

As noted above, assemble your own is much less fraught than it used to be. That is likely a major contributing factor to the custom-build shops around UW drying up over the past few years.

I think you should absolutely build one yourself, just so that you can see how easy it is. Compatibility with Linux is almost always 100%, and since most Linux drivers are in-kernel you won't even have to install anything from the manufacturer. DOAs are extremely rare, and almost anything you buy will be compatible with everything else.

As for the assembly itself, there are no complicated skills required there, and certainly not hours spent screwing things together. (There are 9 screws for the motherboard, two for each hard drive and four for the power supply; several minutes with a screwdriver at most).

Everything is low-voltage, so there are no special precautions to take. Even ESD is unlikely to be a problem. Plugs for different purposes are not interchangeable, so you can't plug anything into the wrong place (well, you could accidentally mix up the power and reset switches, I suppose, but it wouldn't break anything).

That said, a cheap case can be more frustrating than a good one. I bought a "Fractal Design Define R5" a few months ago for my latest computer, and I think it's superb. Aside from one minor quibble, everything in this case is perfect.

Also, there's no reason to avoid ECC, you might as well go for it. If you truely only want a mid-range cpu, then go with AMD. They all have ECC support, and at the moment they're all mid-range compared to Intel. The other alternative is to splurge and get a nicer Intel CPU which has ECC plus other nice toys like VT-x. Plus, going for a faster CPU now puts off your next upgrade a year or two.

Have fun!

On component failure, I think I've had 1 failure in 3 out of 3 builds. And they've not been DOA, they happened after a week. I guess it's bad luck (and I am including a monitor), but not too far out of the ordinary. It can be annoying when you have a boot failure and had to decide which component to return (at my own risk). Or it's the hard drive that fails after a week.

TBH I'm probably more annoyed by my invariably missing a connector or something, and going through a few cycles before it boots right.

I expect the more local shops disappeared with the rise of laptops? I agree you could absolutely self-build. I wouldn't push you towards it though. Maybe different if you're at the start of your career as a tech nerd :). It's nice to have done it, once.

If you've checked GPU support on a prebuilt machine (including the connector I guess, in case of hidpi) - I think the worst incompatibility that's likely is a fighty realtek NIC, something which can easily be worked around.

Two chains I can suggest looking at are NCIX out of BC, I had a custom system build by them in Vancouver and shipped to Eastern Ontario with no problems, and Canada Computers, whom I dealt with at their Kingston storefront.

Canada Computer has branches around Ontario, but I've only shopped in-person for parts in Kingston. I never bought an entire system from Canada Computers myself, but a coworker did buy a high-end custom gaming system, and was happier with it than with his top-of-the-line Alienware system.

I've had better reliability with custom selected white box systems, regardless of whether I've assembled it, or had the store staff do it. As far as I'm concerned using high quality component for the power supplies, RAM, and motherboard has ended-up with a much lower failure / frustration rate. Those components are often neglected in prepackaged white box systems that are built to a price point.

For self-assembly two pieces of advice I can give is use a decent (mostly $50+) quality case to avoid cutting yourself on the sharp corners of a cheap case, and remember to apply a thin layer of heat transfer compound to the CPU if the heatsink/fan assembly doesn't include a thermal pad. I believe all heatsinks included with current CPUs include a thermal pad, so unless you use an aftermarket heatsink, the compound is unnecessary. I would echo the Fractal Design recommendation, as I find them quiet, quality cases with a nice plain aesthetics.

I find the miscellaneous poorly documented case-to-motherboard connectors annoying but workable, but the relatively new 19-pin USB3 header is actually pretty fragile, especially compared to the sturdy connector you are supposed to jam into it. I broke one pin off one such header recently - it was probably bent a little bit to begin with, but it's difficult to see that when inserting the connector.

My suggestion is build a machine using a SuperMicro mainboard and possibly with a SuperMicro case. I've built probably six or seven boxes and learned (the hard way) that excellent quality components are worth the money. The worst mistake I ever made was buying a cheap China box with the idea that it would be good enough for a low-importance application--endless glitches and crashes; had to replace it. Second worst mistake was buying a UFI gamer mainboard. UFI exited the business and the board fried from a minor static discharge several feet away from the case. Recently I found out that an otherwise nice Dell that I upgraded incrementally and morphed into a critical system had a cheap 230W power supply that, when wind took down a nearby powerline destroyed three hard drives.

With SuperMicro you can obtain leading-edge engineering and features with a BOM and design quality intended for filling rows of racks in data centers. Performance will be conservative but reliability will be top-notch and you are guaranteed at least a five year time-horizon where the product will stay in production in case something dies. After production ends plentiful spares can be had on eBay for another three or four years. [I have no connection with SuperMicro other than having built my two favorite machines with their components.]

Pick a Xeon rather than Pentium for the ECC memory and of course go for ECC DIMMs. Suggest a high-core-count uniprocessor for the virtualization potential. Maybe purchase a two-way board in case virtualization goes well and you want to add another CPU when the price comes down. I find the latest Intel CPU MPX capability of great interest and perhaps you may as well.

Building systems can eventually become tedious, but the the first couple are great fun so go for it.

P.S. on the SuperMicro recommendation: You probably know this but don't buy a 1U or 2U rack-type case even if the mainboard might fit in one. These high-density units generate insane amounts of high-pitched fan noise. Some of the SuperMicro cases are 4U and can function as a tower, should be quiet. I've mostly purchased Antec cases and while they may not be penultimate, they've worked well for me.