That will not fix the problem if you have a Studio display. Read the other posts about this problem.
This is from my previous post (from Apple):
"It is indeed normal. The Blue & White computers had the same display driver as Mac OS 8.5, which is why you do not see this behavior there. The newer driver in 8.6 does this, and it is the same behavior that older Power Macintosh computers got with the AppleVision displays in 8.5 (and 8.1 for that matter). It is a newer display driver than what you have in ROM, and therefore it has to load. If you start up with extensions off, it doesn't load, the display is not being driven properly, and it stays in 640x480. No patch will be released to change it, since it is behaving as we expect it to,and using the new driver."
Forum Leader - Apple Support Discussions
Oh yeah you can install the monitor CP from your 8.5 cd, it will be in the monitor extras folder after you install it.
[This message has been edited by kuntz (edited 05-14-99).]