There are several places where this might be configured. (This may differ between versions, so please specify which version you are on.)
To start with, in the management snap-in you have the following:
Publisher Settings -> Root storage folder
General Settings -> Temporary Path
I don't think the default Tridion.ContentManager.config file has any reference to temp directories, but it's worth a check.
Then you have the CD configuration files, for example cd_deployer_conf.xml - on a development box, there may be several examples of these for different web applications, and don't forget the logback configuration files.
Of course, it's always possible that there's some Tridion code that doesn't use a configuration setting for this, in which case you'd need to contact support, but I'd think these days that should be unlikely. (I have a vague memory that the tcm protocol handler used to use the temp directory, but that's a long time ago.)
For something that's occurring during publishing, don't forget your own implementation. What about your templates, events system code etc.
To analyse this kind of problem, I would highly recommend the Process Monitor utility from SysInternals. You should be able to isolate exactly which process the writes are coming from.