Well, I've done this once.
Had (initially) to upgrade just about everything in my computer because it was time to go from AGP to PCIe x16 for the graphics card.
This was when Athlon64 was "the
<Mod Edit>", and available on three different sockets:
- Socket 754 was the oldest.
- Socket 939 had been the higher end.
- Socket AM2 had just been released.
AMD said one of the older sockets was to be dropped, but support (with new CPUs) was to continue for at least 18 months.
Since I was a bit short on money and had to prematurely get a new graphics card and not "only" CPU, mobo and RAM my plan was to initially buy a single core CPU and replace it with a dual core at least one year later.
What socket should I pick?
- With the trouble surrounding the Nforce2 chipset I was reluctant to become a guinea pig for some brand new platform (AM2).
- Socket 754 was old, and seemed most likely to be the one to be dropped.
- Socket 939 was well proven, so that became my choice.
Soon after my purchase AMD announced that it was Socket 939 they were giving out on, keeping 754 for the low end CPUs.
Some three to four months later I noticed that the Athlon64 models for Socket 939 were becoming rare in the stores. I now had to move quickly! Ordered a dual core from one vendor that some two weeks later had to tell me they couldn't deliver. In near panic I then ordered from another vendor and was able to snatch one of the last Athlon64x2 for Socket 939 available in the country!
That CPU then served me well until it was replaced by a Core i5-2500K. Had I not done that panic upgrade I would have had to get another (AM2) mobo and CPU much sooner.
I think my points are that...
a) ... it makes sense to do buy into a platform at the end, if the alternative isn't proven and you want reliability, and...
b) ... starting with a low end (here earlier generation) CPU and then upgrade about one year later can be perfectly valid from a cash management perspective.