Please don't get me wrong here, I'm not getting into anymore of 'should I run 32 or 64 bit?' stances, because most of us will run what our hardware allows, or whatever we feel like running, it's our personal decision. Plus some needs 32 bit for legit purposes, to include Linux 32 bit OS's.
While it was a tough call to make, the Dell Dimension 2400 that my now deceased mother-in-law gave me sat in a box in the corner of the closet for nearly 4 years, once I purchased a XPS 8700, powerful for it's day & has also been upgraded. I then pulled it out one day & tore it down, the intention was just to clean the PC up & reinstall XP like new & then Linux Mint 18.1 Xfce. By chance, despite all of the talk on the Dell Hardware forum that 'major case mods' were needed to upgrade the MB, all that involved was the removal of the four standoffs disguised to be proprietary & the removal of that ugly green shroud that served as an AIO cooler for both the CPU & exhaust fan. Once those were out of the way & case cleaned up, an ASRock 970M Pro3 mATX dropped right in, after installing the I/O shield, as though the case were designed for it. So much for 'major case mods' declared needed by the Forum's 'Rockstars'
Once the SSD & HDD was installed, vertically, as well as PSU swap, the connector for the power & front USB ports plugged perfectly into the MB panel for it & booted on the first try via Linux Mint live USB stick The only thing I've yet to figure out & may not bother, is the front mic & headphone ports, it's just a bunch of tiny wires held together by a proprietary plug & hard to find the info as to where to plug each in (why fix what isn't broken? ). At that point I knew that Dell not only lied on their forum (some posts were made by employees), also built the PC to underperform, at the time (2004) there was better hardware on hand, as DDR2 RAM had been introduced & early Core2Duo series CPU's. Performance would had been tripled with only $100 in upgrades, given large OEM's pays much less per component than we do. When we lookup an Intel CPU's specs & see the recommended price, this is for large OEM's purchasing in lots of 1,000 or more & it's across the board for everything.
While it's not running a NVIDIA GPU yet, am only one upgrade away on one of my main ones, a GTX 1060 (6GB variant) will also be installed & along with the FX-8350, will be a very respectable PC. I firmly believe that my mother-in-law, whom I felt towards like as though the mother I never had, would be proud of my work, if she were here to see it today. There's software that can be used to make it look like a legit Dell (or other brand) on the Windows Club site, called 'Ultimate Windows Tweaker', used properly, can name a PC as desired & get rid of 'To Be Filled by O.E.M.' and can even list the OEM's phone, website & hours of phone operation. Folks who knows little about computers will be amazed at the speed, because they won't know that the ancient 32 bit MB & other components were stored in a box & all new installed, and in line with topic, can stuff a GTX 1070 in there & have up to date support, even running Linux.
So just like this Dimension 2400, there's likely a lot of 'sleepers' out there. I seen a YouTube video created by Linus Tech Tips where a mid-1980 Apple PC was completely rebuilt w/out any exterior cosmetic changes (other than a fresh coat of paint). Build was complete with a much newer CPU than the FX-8350, custom water cooling, GTX 1080, the whole nine yards & one waling by wouldn't know the difference. Yet the user will & that's my point, going back to all of these sleepers on the market, while not all can be upgraded, many can be & keep the original look, like back in the old days, many of us with autos & trucks that had a 6 cylinder engine would drop in a 350V8 or similar sized one in. It's fun. and the good thing is that the older components can be sold to one who wants these bad enough.
While I know that for today, maybe even a few months to a couple of years, this NVIDIA deal may not seem like much, believe me now or regret it later, these open source drivers doesn't take the place of proprietary ones, even on Linux. That's why for now, I have Mint 17.3 installed on my AMD GPU's, just to have the Catalyst Control Center, w/out it, fine tune adjustments cannot be made. Will have to look for some NVIDIA OEM cards (one being the GTX 645), although these will require more power than some of my SFF PC PSU's will provide, still there's a couple that I can upgrade. Plus a possibility that a local shop who specializes in AC/DC motor repair can w/out modifying the small PSU case other than drilling more intake holes on the inside of PC & adding a faster fan for cooling, can turn a 240W one into a 350-400W model, although this is a costly service. A friend in the PC business is finding out what he can do for me. even if it has to be performed in his name. This would allow me to ditch (some) of these AMD cards & move to the GTX 645 OEM single slot card, which is not only supported by 64 bit OS's, also are 4K compatible, meaning that these will perform even better on a fast 2K monitor, an item that I want for 144Hz refresh rates. Open source and performance doesn't belong in the same sentence, until the former can add custom controls to fine tune everything (kind of like Pulse Audio).
BTW, I also have a GT 210 card, yet trying to get decent performance out of it is as though squeezing water out of a rock, few runs 64 bit GPU's anymore, other than those on a shoestring budget or doesn't know better, wastes a lot of power also in all of the excess heat. Got to have a minimum of 128 bit card to do much anything productive, preferably a 192 to 256 bit model these days for today's demands. NVIDIA has also began (long ago) not providing the latest drivers for these older cards, even on a 64 bit OS of any type & AMD has done the same on the other side.
At any rate, if one's happy where one is, that's fine with me, am simply providing fair warning that running older hardware does pose significant security risks, regardless of the OS ran, to include Linux. Here's an article from last year by a reliable source which points this out.
BTW, there were other cool technologies new today to Windows users which were ran on 64 bit Ubuntu 12.04/Linux Mint 13 LTS (not retired), such as 1st gen NVMe SSD's, long before consumers heard of these, with an old (early 3.xx) kernel. There's many things that are tested on Linux today before shipping to the masses, although today not on 32 bit hardware. Even most smart TV's are powered by 64 bit Linux, those who has one knows all of the great features inside, as well as a fast growing non-Apple smartphone market, where Apple is losing grip due to price & outdated features for a high premium, OEM's who uses the Linux platform, Google OS is based on Chromium OS, which is free open source software & anyone can install on many notebooks, it's just that some Google proprietary features may not work.
We're in a fast paced Tech World, the time is coming fast, there'll be a day when these OS's may not connect to the Internet, as partners of Microsoft, Apple, Linux & others will simply stop supporting the platform. While some may enjoy these for now, when the day arrives that one cannot access email or make transactions on 32 bit computers, that's when reality will set in & most who still wants these will carefully box & store to prevent aging from light, dust & other factors. I have one near 15 year old IBM T42 notebook that am about to donate, it's taking space, and although Mint 17.3 runs fine on it, as does XP & W7 if Vista drivers are installed, slow as molasses for my usage, am used to having computers booted & have the browser open in under 30 seconds, models with IDE spinners, even at 7,200 rpm, just can't make it. Drivers are crummy also, at boot lots of red where there was once a normal screen, the XP side doesn't do this.
The 32 bit era is ending........at a faster rate than some may think, we'll see what happens once Ubuntu 18.04 ships & how Mozilla will deal with their 32 bit Linux browser on OS's still supported. By supported, that's no guarantee of future browser upgrades, only security updates for the OS.