15 minutes to boot into Windows?

As far as PSU detail - It doesn't appear to be detailed in Speccy

Try the on-line manual at your manufacturers webpage. HP does specify the PSU there.

yea, opening the case may be the only way, but its the big box with wires coming out of it. you say the computer is only slightly slower than normal? don't rule it out, but perhaps it isn't a hardware issue. you've updated everything in windows update and all drivers (device manager and devices and printers don't display any yellow exclaimation points?):

basils57 said:

Thanks Dusty; The time that this problem started probably equated to the time that the original HD started to play up.

When was this? how long? The only common link between the two things would be time, not the installation of a program?

basils57 said:

My new HD is new, not used, and once booted up the computer seems to operate as normal - albeit slightly slower than normal, and with a problem reading my Win7 installation CD!

Have you upgraded the hardware anytime soon?

You know the best way to test if the HDDs have a problem is to plug them into another computer and see if they work well or not. Keep in mind a 15 minute boot is not often a failing harddrive. it could be anything from a virus to too many programs taking too long to load up. Is your computer generally slow or fast? I feel like there is some information that is missing. Could you explain more fully the problem, from exactly what happens, if it stops or continues, the similarities between it and the previous problem, any strange looking things found under programs in control panel that you don't know what they are... you have an antivirus fully updated and functioning? perhaps add malwaebytes to it for an extra scan. Only 1 antivirus (adding malewarebytes in addition is fine) at a time, right? which one? I recommend MSE for simplicity and a great AV, but you can make your own decisions in that area. you have all windows updates, including malicious software removal tool found in windows update but also through that link? PLease give as much info as you can, might help us find the culprit a bit faster. Let me know what you try, perhaps we can find a way to fix this