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Diagnostic Tools

I'm looking to start up a PC repair service and I need recommendations for good diagnostic tools. Preferably something that is cheap / free, or something that can be licensed for use across many PCs at a reasonable cost, since I imagine I can't just buy one copy and use it on all my customers PCs.
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Top Expert 2009

You're going to get a LOT of answers to this one.  My choice of best free tool is the Ultimate Boot CD for Windows.


What is the Ultimate Boot CD for Windows?
UBCD4Win is a bootable CD which contains software that allows you to repair, restore, or diagnose almost any computer problem. Our goal is to be the ultimate free hardware and software diagnostic tool. All software included in UBCD4Win are freeware utilities for Windows®. UBCD4Win is based on Bart's PE©. Bart's PE© builds a Windows® "pre-install" environment CD, basically Windows® booted from CD. We include many free hardware and software diagnostic tools that allow you to fix almost any problem you will face with your computer. With network support, the ability to modify NTFS volumes, recover deleted files, create new NTFS volumes, scan hard drives for viruses, etc. this project includes almost everything you need to repair your system problems. This project has been put together to be the ultimate recovery cd and not a replacement OS (Operating System). Please visit the "List of Tools" page for a complete list of what is included in the latest version of the project.

dbruntonQuid, Me Anxius Sum?  Illegitimi non carborundum.

And of course the UBCD http://www.ultimatebootcd.com/

Sysinternals http://technet.microsoft.com/en-us/sysinternals/default.aspx All their stuff is good but you must have Process Explorer at least.
you will also need a test rig back at base to load client drives and  recover data
also a set of malware , virus removals,
plus power supply tester
Top Expert 2009

Two free tools I just downloaded that look good but haven't tested yet are the Avira AntiVir Rescue System and the BitDefender Rescue CD.  Read about them here:

Most Valuable Expert 2012
Hello IHumble

Another humble submission:


Top Expert 2009

Another tool I've used in the past is called Emergency Boot CD, but it is no longer free.  You might want to take a look at it anyway.  Then there is BartPE, upon which the Ultimate Boot CD for Windows is based:


What is BartPE and PE Builder?

Bart's PE Builder helps you build a "BartPE" (Bart Preinstalled Environment) bootable Windows CD-Rom or DVD from the original Windows XP or Windows Server 2003 installation/setup CD, very suitable for PC maintenance tasks.

It will give you a complete Win32 environment with network support, a graphical user interface (800x600) and FAT/NTFS/CDFS filesystem support. Very handy for burn-in testing systems with no OS, rescuing files to a network share, virus scan and so on.
This will replace any Dos bootdisk in no time!
Technology and Business Process Advisor
Most Valuable Expert 2013
What, EXACTLY do you want to diagnose?  Hardware?  Software?  The OS?  Active Directory issues? What?

I would suggest you start with my page on the Technician's Tool Kit - www.lwcomputing.com/tips/static/techtoolkit.asp
Top Expert 2009

Wow!  THERE is a page that immediately goes into my Favorites (which is where I keep a categorized list of all web pages I've found useful about computers and the internet -- several thousand different sites, by the way).  No wonder you're so highly ranked at Experts-Exchange, leew!
Lee W, MVPTechnology and Business Process Advisor
Most Valuable Expert 2013

Yeah... just gotta get back to updating it... haven't done serious updates in about a year or so...
dbruntonQuid, Me Anxius Sum?  Illegitimi non carborundum.

Here's one more for you leew

Top Expert 2007

Then there are the times when the PC won't boot and you need to figure out what is wrong.
This is a printable flowchart for troubleshooting hardware problems and the logical steps to take to identify the troublesome hardware device.
There are also specific flowcharts links for certain parts that can be accessed here.(they are part of the larger flowchart)
Distinguished Expert 2019
for diags, you can use microscope2000  http://www.micro2000.com/
or PC-doctor : http://www.pc-doctor.com/

but you can use also a burnin test : http://www.passmark.com/download/index.htm      
great soft for testing a running rig !

and a FREE live cd like Knoppix is very good for testing hardware : lan, internet, USB
download from www.knoppix.net the latest version in your language !

or buy the best ERD Commander from MS http://www.geekstogo.com/2009/01/17/erd-commander-free-trial-from-microsoft/

for doing system restores, accessing/modifying OS files, and data copying

also, HDD regenerator has helped me to recover 2 inaccessible disks (none came back up to now !) :
If you are planning on working mostly on domestic pc's, the majority of your work, like mine, will involve removing malware and cleaning up afterwards.

A good boot disk ( as suggested above ) is essential. I use UBCD4Win, but I also have ERD Commander and Bart PE in my toolbag.
To remove malware, two very good utilities are:


These are free for domestic use but you should buy the paid version to use them commercially;

A rootkit scanner is also essential. I use Unhackme:


Simple, easy to use and very effective;

Another great diagnostic for malware detection is Hijackthis:


There is a good HJT tutorial here:


This site also has a great tutorial for a tool called Combofix, which is very highly regarded:


This a great tool, but rather fierce.  You should be absolutely clear about how to use it before unleashing it on a customer's computer.

Simple hardware diagnostics are also useful. These two are highly regarded:


I hope this is helpful.