If you do happen to use a Brisbane-cored 2.1 GHz Athlon 64 x 2; your existing BIOS may not recognise its architecture. The chances are, from my experience, that it’ll still work reasonably well if you can force the BIOS to accept it anyway; but stability could well be an issue.

The best thing to do if intending to use a Brisbane-cored Athlon 64 x 2 on an older motherboard would be to check that there is a BIOS upgrade available before purchasing the secondhand Brisbane-cored processor. If a BIOS upgrade is available then either get an experienced geek to flash your BIOS for you, or risk doing it yourself if you’re brave enough, after installing the new CPU and receiving the message that the old BIOS doesn’t recognise the architecture. (I’ve flashed a considerable number of BIOSes and only cocked-up once AFAIR; at the worst possible time. The result was that basically the motherboard was rendered worthless…But that’s another story.)

If you get the message that the new CPU’s architecture is unrecognised, but there isn’t a BIOS upgrade available for your board; then the choice is either to try and stick with the situation regardless, or to remove the Brisbane-cored Athlon 64 x 2 and insert a Windsor-cored Athlon 64 x 2: The choice is yours.

The better option in this case is to fit the Windsor-cored CPU, although either option may or may not produce satisfactory results.

*End of addition.

If, on the other hand, your motherboard will support the operating frequency of your desired Athlon 64 x 2 and you have no problems acquiring it new then go for it. If you can’t find an OEM package and can only get a boxed processor in that model, complete with a cooler heatsink/fan, then do so. It won’t hurt to replace the cooler as well as the CPU.

Having acquired your replacement CPU after doing all these checks; you now come to the practical bit; i.e. fitting the damn thing:

It’s not exactly brain-surgery or rocket-science to do this; but you’ll need to prepare yourself beforehand. Here’s what you’ll need: -

• Screwdriver; if you need to remove or loosen screws to remove the side-panel of your computer’s case.
• New processor at the ready. Leave it inside its packaging until the very last moment.
• Thermal paste. You’ll need this to paste onto the surface of the new processor after you’ve fitted it into the processor socket and before you fit the cooler onto it. If your replacement processor came boxed with a new cooler then chances are that the paste is pre-applied to the cooler. The amount pre-applied should be adequate (Some computer-builders would disagree with me here; but I’ve always found it to be so.). If on the other hand you’ve bought an OEM or a secondhand processor then you’ll need to apply thermal paste as above.
• An anti-static wristband connected to electrical earth. If you don’t have one you might be able to use a crocodile-lead and connect a piece of metal jewellery or a watch that you’re wearing to the computer’s case, provided that the computer’s case remains earthed.
• Finally a positive calm attitude: I personally find it a good idea to meditate for a short while before any computer-work in order to achieve a level psyche so that I don’t panic or do anything wrong during the operation through lack of concentration. Forget the gas bill, forget your boy or girlfriend for the time being. Ensure that you won’t be disturbed for a while, adopt a levelled and intellectual thinking-pattern, and we’re off.

Ensure that the switch on the computer’s power-supply unit (Usually situated at the back of the computer.) is off. If it is off but the power-lead remains connected then the case is earthed. If you disconnect it then the case is not earthed or only partially earthed. Open the computer’s case by removing the side-panel.

You will notice the (black) cooler fan protruding from the board. On one of the sides of the cooler, near the motherboard’s surface, you will see a lever connected to a clip on the cooler heatsink. Pull this lever to the upward position. You will see a pair of wires (Maybe three(?)), (Probably red and black (and white(?)).) leading from the cooler’s fan to a small plug in a socket on the motherboard. Remove the two or three-pinned plug.

Release the clips; one under the lever, the other diametrically opposite it on the cooler heatsink. The cooler heatsink and fan should now pop-off the board, with maybe a little upward pressure, to reveal the existing processor seated in its socket.

On one side of the processor you will see another lever. Lift this lever into the upward position and carefully remove the old processor from the socket without touching any of its pins. You may wish to retain this processor. If so it would be a good idea to place it into the new processor’s packing after the new processor has been removed from it.

Carefully remove the new processor from its packaging without touching any of the pins. Insert it straight into the waiting empty socket, ensuring that the marked corners of both the processor and the socket are lined up. Place your old processor into the empty packaging.

Once again check that the marked corners of both the processor and the socket are lined up. Also ensure that your anti-static wristband or otherwise is connecting your body to electrical earth. Apply slight pressure to the processor’s surface and push the lever downwards into the position that you originally saw it in when you removed the cooler from the old processor. If anything resists your attempts DO NOT FORCE IT. Recheck that you are doing the operation correctly and try again.

If you have bought a secondhand replacement or OEM processor then you’ll need to re-use the old cooler. Gently and carefully, trying not to cause any scratches, clean the upward-facing surface of the processor. (Do not wipe the markings off. – You don’t need to clean it that well!) and also clean the underside of the cooler that will end up on top of the processor, Apply a very thin layer of thermal paste to each surface. The edge of a credit card will assist you to keep it thin. You may notice that it seems slightly thicker in some places than others: This is normal. The paste is filling the gaps that would otherwise be left free of contact between processor and cooler.

If you bought a new, boxed processor complete with a new cooler; remove the plastic cover to expose the  pre-applied thermal-paste.

Place the cooler on top of the processor and slide around a little to ensure that it’s located in exactly the right place. Locate the two clips diametrically opposite one another on the cooler with the lugs on the socket. Push the lever back into its original position: flush with the motherboard’s surface.

Connect the cooler’s fan by plugging the plug into the appropriate socket on the motherboard.

The operation as regards hardware is now complete.

If you removed the power lead from your computer’s power socket; replace it and switch the power switch on the rear of the computer back on.

Power-up your computer and immediately insert your Windows or other CD or DVD.

Perform a maintenance-reinstall of your operating system and re-download any patches and updates provided by your operating system’s manufacturer.

Your computer should now be running both cores of your new processor. To check this in Windows XP, press Ctrl+Alt+Del simultaneously. The Windows Task Manager should display two performance graphs: One for each core.

If you have any problems with this, or you are unsure of anything before you start then consult a professional geek first before doing anything.

See also: Problems upgrading to a Phenom.