So I have actually been asked about building a gaming PC in the last week by multiple people. I love building my own machines, but I have been torn recently due to the pricing on the used market of high end workstations.
I have been checking the Build vs. Buy question bu building a few sample configurations, and then looking for a few really good workstations and my view right now is that I can get a pre-built killer gaming machine for roughly 1/2 the price when I buy (or the same price with double the performance). Let me go over the criteria I am using to make this decision.
Firstly. I am NOT talking about buying a machine that was ever originally built as a gaming machine, but instead machines that started out life as high end corporate Video Editing or CAD/CAM/Modeling workstations. This is because a high end gaming machine might top out at $4K or $5, but a high end CAD or Video Editing machine might start out at $10K. Its a whole different class of customers.
Secondly Technological power doubles about every 18 months, however depreciation of hardware halfs about every 10-12 months. The used equipment depreciates in cost about twice as fast as the performance of the market catches up.
Ok, lets look at the many things to consider when getting a PC. Firstly if you build your own you need to get a Motherboard and CPU Combo. For gaming you want something like an i9, and likely something with at least 8 cores ($300 range) or 12 cores ($500).
The middle or upper machines in the toms hardware guide are listed here https://www.tomshardware.com/best-picks/best-pc-builds-gaming and they are pretty good buildouts.
Then you need to select your Motherboard to match the socket and the CPU. Note that the cheaper motherboards may lack USB3, may lack PCI card slots, or limit the number of lanes that are available. A lower end motherboard may only have a single 16 Lane PCIe slot, and another 1 lane PCIe slot. This matches up with desktop consumer class CPUs, Lets look at a Intel Spec Sheet. https://www.intel.com/content/www/us/en/products/processors/core/i9-processors/i9-10850k.html/i9-10900t.html notice that the version of PCIe is 3.0 and the number of lanes is 16. This means that even if the motherboard supports PCIe 4.0, your CPU defaults it down to 3.0. This may be a concern if you intend to add a second video card, or add a video capture card, or high end networking card, or SSD Card, etc.
Another consideration to make is the memory requirements, notice that max memory is 128gb, and 2 channels for the memory at DDR4 speeds. Keep this in mind.
Also note that the CPU does not support ECC memory, which is self correcting, but supports Parity memory. If parity memory errors are detected, the machine will BSOD (Blue Screen of Death), however ECC memory will catch single bit errors, and repair them without the OS encountering a problem. The Added cost for ECC however usually keeps it out of consumer class, and only in enterprise equipment.
Another limitation of these consumer class CPUs is that they are limited to single Socket operation, meaning you commonly (99.9%) of the time have a motherboard with a single CPU socket, and that one CPU is all you get. Enterprise Class equipment commonly has dual socket, but the CPU must support dual operation.
Another consideration to make is your case. The case will range from $80 to $160, and the different cases will have different feels to them, some feel like cheap tin, others feel like substantial aluminum systems. A Good case is important for cooling and noise.
Supporting large fans or water cooling sounds like something that would actually create more noise, but its the opposite, the smaller the fan, usually the faster it runs, and the noisier it is, larger fans are usually nice and quiet while moving good airflow. Water cooling however, eliminates the need for as many fans, and (a good one) makes far less noise. Nobody likes a loud PC. Water cooling however can break the bank as they may be a bit pricey.
If I were recommending building your own machine however, I would follow this guide, as it is pretty optimized, but I would avoid the low end $500 unit as the CPU in that is only slightly better than a Doritos.
Now, lets talk about high end workstations and how they hold up. The following listing is an HP Z840, https://www.ebay.com/itm/HP-Z840-Workstation-12-Core-2-40GHz-E5-2620-v3-32GB-No-HDD-No-OS-/184529907307?hash=item2af6d6ee6b
and the important specs are Dual Socket Motherboard with 2 x Intel Xeon E5-2620v3 (6 Cores) Specs here https://ark.intel.com/content/www/us/en/ark/products/83352/intel-xeon-processor-e5-2620-v3-15m-cache-2-40-ghz.html and to get the specs on the chassis see https://support.hp.com/us-en/document/c04505606
buts its a mixed bag….The clock speed is only 2.4Ghz, but you get 12 Cores, since you have 2 x processors, and each Process has 40 x PCIe 3.0 Lanes, opposed to only 16, this means that the motherboard that supports it has many 16 lane slots instead of just 1. It also takes DDR4 memory, but each CPU has 4 channels, so instead of 2 or 4 memory slots, you get 16 memory slots. and it also uses ECC memory. In this build it comes with 32GB of ram already installed but can max out at 768GB RAM per socket. All in all, a different class of machine. All this for $600
In addition to this, you get an extremely well built aluminum case, that has well designed airflow for max cooling, and CPU heat risers to keep it quieter. To this machine I would add a $80 SSD (like Samsung 860Pro 256GB 2.5″ SATA), and a $330 Video card (such as MSI GeForce RTX 2060 Ventus XS 6G).
Many of the difficulties that come about from building your own also disappear since you can find proper drivers and proper integration.
Here is a good review of the Z840. Note: don’t get the Z820, its much cheaper, but is DDR3….unless that massive price drop is worth it, it may well be. You can get into a Z820 series that is still a very good machine for roughly $300 total, with a similar amount of memory and similar Core Count, but fewer PCIe lanes (and PCIe 2.x), and lack of USB3 portsDDR3 which makes the memory 1/2 the speed, and likely 3 channels instead of 4 channels per CPU. The Z400 series drops to single socket,
Again, this is all about reading the spec pages. There are plenty of other Z840s on Ebay for sale, some only have one socket populated, other have no memory, or no CPU, just read the spec page. I have had a lot of luck with the seller https://www.ebay.com/usr/digitalmind2000?_trksid=p2047675.l2559 as they have good descriptions.