There are three versions of the HP Compaq D530.
1) The Convertible Mini-Tower Desktop PC
2) The Small Form Factor Desktop PC (SFF)
3) The Ultra-Slim Desktop PC
http://h20180.www2.hp.com/apps/Lookup?h_pagetype=s-001&h_client=S-A-R163-1&h_page=hpcom&submit.y=8&submit.x=6&lang=en&cc=us&h_lang=en&h_cc=us&h_query=HP+Compaq+D530&x=7&y=10The reason I bring this up is that if I knew what EXACT desktop computer you have, I could give you exact information on how to access the CMOS Battery, and replace it.
I'm going to use the Convertible Mini-Tower Desktop PC for an example,
http://h20000.www2.hp.com/bizsupport/TechSupport/Home.jsp?lang=en&cc=us&prodTypeId=12454&prodSeriesId=316720&submit.y=8&submit.x=6&lang=en&cc=us&y=10&x=7
In the list click on >
Manuals, (guides, supplements, addendums, etc)
On this page scroll down to the bold heading > Service and maintenance information
Click on the file name >
HP Compaq Business Desktop D500 Service Reference Guide, 5th Edition
Allow the PDF file to fully download.
Use this same procedure on the HP Compaq D530 you have.
In the Bookmarks menu to the left, scroll down until you come to the heading >
Removal and Replacement Procedures - Convertible Minitower (CMT) Chassis
(If you have an SFF, or Ultra-Slim, it will be listed at the end of Removal and Replacement Procedures, instead of Convertible Minitower)
Now scroll down to > 6.15 Battery, and click on it.
Now go to the pages that follow.
(NOTE* You may wish to reduce the view size. Click on the Zoom Out icon.
{Circle at the top of the PDF file with a Minus ( - ) sign in it }
The CMOS Battery is a CR2032. A type of watch battery, found in an abundance of stores.
If you have questions please post in a Comment.
Regards,
joecoolvette