A computer is the sum of the components. This goes for price and performance.

If performance is the same, lower price obviously wins. If price is the same, higher performance obviously wins. In this case, it's both higher performance and higher cost. So you need a metric for analysis.

If you want to compare system performance, you have to compare system cost. This is most noticeably true for those that consider a PC an active/evolving investment or are building a new PC. (I prefer this train of thought since the product you replace doesn't disappear--you can sell it or repurpose it any way you want)

If you're insistent on the upgrade mentality (and there is some reason to do it...especially if the computer no longer has original worth [i.e., last gen]), then you have to take it as upgrade performance to upgrade cost.

You can't compare system performance to upgrade cost to find worth. Two different metrics. Lowest priced item will always win. In the other direction, you can't do upgrade performance compared to system cost either....better performing product will always win.

Also, the value-scale of a dollar and budget is different for everyone--for these descriptions I'm using linear and non-factor, respectively.