I have been getting a few questions recently about motherboard replacements, especially on older machines and it always brings up the question of whether it is worth fixing/upgrading an old computer or getting a new machine. With new PC & laptop prices starting under $500 the argument for a new machine can be made easily.
From experience I think you can get five good years on average out of a PC or laptop. That is not to say you cannot get more, or that you may get less, but five is a good average. Before the five year mark I would be willing to spend more to fix a machine, but nothing beyond reason. I new PC purchase is always an option and you should go with a 3-year warranty at the least from any vendor. Near or beyond the five year mark I would spend very little on a machine.
Some examples - I have never been a fan of motherboard replacements and see little value given the high cost usually involved. That is not to say I have not replaced a motherboard or two. Generally it has been within the warranty period and the parts came at no cost. Paying for this replacement is very expensive. Unless you find a cheap and reliable used part on eBay or something similar I would advise against this fix/upgrade.
Ditto a CPU replacement or upgrade. I have never understood why people would want to upgrade a CPU. It is expensive and only gives you a modest bump in performance given that your other parts inside the computer may be a few years old.
Some items worth fixing or upgrading? One easy one are fans, which are prone to problems but relatively cheap. Hard drives are worth replacing because costs are low and upgrading or adding a new internal hard drive is always a solid option if you need more storage space. Hard drives are also prone to damage and failure late in life of a PC, so having a backup hard drive or external hard drive is a must for older machines. Adding RAM is helpful, especially near the 3rd & 4th year of a machines life. You can get a little extra performance out of some additional RAM and costs are modest. Certainly keyboards and attached devices are worth replacing if they go bad and this includes a laptop keyboard which can usually be replaced for under $150.
If total costs creep up near $500 you need to consider the new machine. The benefit of a new system, with a faster processor, more RAM and fresh hard drive are too good to pass up for an aging system.