HP Compaq dx2420 Microtower Computer (Windows 10, CPU Upgrade, RAM and Maintenance)

This blog post is about the HP Compaq dx2420 microtower computer covering: Windows 10, CPU upgrade, RAM, maintenance and more. This blog post has been updated in 2019.

Last updated: 12th November 2019

Warning: I’m not suggesting you do anything I did to the dx2420 PC! You perform any hardware changes at your own risk!

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HP Compaq dx2420 Microtower Computer


I’m updating the introduction in November 2019. I used to own two dx2420 PCs, but killed the motherboard on one of them! I’ve placed the dx2420 with the MS-7525 motherboard in my bedroom.

This is an old computer, but I recently added an additional hard drive and replaced the E8400 CPU with a Core 2 Quad Q6600 CPU. Previously I had replaced the PSU and made other changes.

The PC used to have Windows Vista installed. I currently dual boot between LibreElec and Windows 10. I have three hard drives and a DVD writer installed. I’m currently not using one of the hard drives, but might install a linux OS on it.

I have installed a wireless card, but I currently don’t use it and I prefer to use the ethernet RJ45 connection.

The dx2420 isn’t my main computer these days. I quite like the computer and I intend to carry on using it. I suggest you use a PCIe graphics card and not rely on the motherboard’s awful on-board graphics. I wouldn’t use the computer without a graphics card.

dx2420 microtower PC

November 2019 photo

inside dx2420 computer

Old outdated photo

This isn’t a computer for high end gaming and video encoding. So what exactly can you use it for in 2018? Below I will answer that question and provide some feedback, based on use in 2018.

Using Microsoft Windows 10
You can install Windows 10 64-bit edition on a dx2420, but it won’t be good performance. I suggest 4GB RAM and a PCIe graphics card. I use the ATI Radeon HD 5450 graphics card. I’m using a socket 775 Quad 2 Core CPU in the PC (I previously used E5300 & E8400 CPUs). I don’t use WiFi with the dx2420 and instead use the RJ45 ethernet connection.

I used to play multi-player computer games, and have run Broforce, Company of Heroes, Red Alert 3 and Towerfall. My fiancee used to run the Nox Android emulator to play Paradise Bay.

This isn’t a computer for high end gaming or fast video encoding. I have used Corel VideoStudio X9 and Corel PaintShop Pro X9 (64-bit).

I also optimise Windows 10 for performance, which does make a difference. I turn off some visual features, disable some services, customise the start up and have no desktop wallpaper.


The rear of the dx2420 has the following connections:

  • Three audio sockets (line-in, microphone and speaker).
  • 4x USB ports
  • 1x VGA
  • 2x PS/2 (for keyboard and mouse)
  • 1x RJ45 Ethernet

dx2420 rear connections

Hard drives

Note: The next two paragraphs and photo are outdated. Please scroll down for a November 2019 update.

I’ve never used a SSD in this computer and I’ve only used SATA hard drives up-to 250GB in size. There is room to fit a couple of 3.5″ hard drives in the 3.5” drive bays.

dx2420 BIOS

My dx2420 has a DVD drive in a 5.25” bay with a second 5.25” bay empty. So I guess you could consider using a 5.25” to 3.5” adapter if necessary. My typical setup is two hard drives and a DVD drive (and using the second 5.2″ bay to store a disconnected spare DVD drive).

November 2019: I now have installed three hard drives in a DX2420. The latest hard drive isn’t in a caddy in the top 5.25″ bay sitting on top of the DVD drive! I’ve installed an old wd5000avvs-63h0b 500GB SATA hard drive.

Hard drives Phoenix AwardBIOS

To help maximise the performance of this computer, maintenance is important. The state I let my CPU heatsink and fan get into wasn’t good. All the dust in the photo below would have been affecting the temperature and performance.

dusty heatsink and fan

November 2019: I ran the free version of CCleaner in Windows 10, made a backup of the registry and then had it repair the registry. Afterwards I uninstalled a lot of software I don’t use.

I normally don’t upgrade a motherboard BIOS unless I’m forced to, but this time I decided to. I was originally running BIOS version 5.18 02/20/2009 and then flashed to 5.31 10/06/2010. The 5.18 and 5.31 BIOS versions don’t have options for overclocking.

dx2420 bios flash

If you want to read my blog post about a dx2420 motherboard BIOS flash, please click on the link.

I own two dx2420 computers, but I recently killed the motherboard in one of the computers. I then replaced the motherboard with a model meant for a dx7500. Click on the link to read about replacing a dx2420 motherboard.

Note: I did once install a GeForce GT 710 graphics card and it didn’t work too well, but I’ve not tried it since flashing a newer BIOS.


Note: Scroll down to read about a Core 2 Quad installation.

If you’re thinking about replacing the CPU, click on the link to read about my dx2420 CPU upgrade.

CPU on motherboard

Note: This paragraph is outdated (please scroll down to read about a Core 2 Quad CPU) At the time of writing, I’m not sure whether I should have upgraded from a 2.6GHz to 3GHz CPU, despite the increased performance. If I had originally been using a sub 2.4GHz socket 775 CPU, I think it would have been a great upgrade.

CPU-Z E8400 3GHz

CPU-Z with E8400 3GHz listed

Installing a Core 2 Quad CPU in a HP DX2420 Microtower PC (MS-7525 motherboard)

Please note: A long time ago I replaced the PSU in my PC with a higher wattage PSU, because the original PSU died.

This section of the blog post was written in November 2019! I managed to get a Q6600 Core 2 Quad CPU working in a HP DX2420. 

I was being naive as whilst I had checked HP’s web page about supported CPUs, I hadn’t looked at the microcode list in the latest BIOS.

I had previously flashed/installed the MS-7525 5.31 Rev A BIOS (you can read about that here), so I decided to use the application ‘intelmicrocodelist’ available via a link from this web page, to read what CPUs are listed in the 5.31 BIOS.

If the CPU IDs at CPU World are correct, then it lists a X5355, E5440, Q6600 and a Q9550! I was absolutely blown away by what I saw.

I already know that other people with a modified BIOS had been running some Xeon CPUs, but could I run the Q6600 with the official released 5.31 BIOS I already had installed? The quick answer is yes!

Intel Q6600 Core 2 Quad CPU

I installed the 775 socket CPU in the motherboard and when I booted I saw the message “ERROR : Unsupported CPU installed. PC will automatically power down in a few seconds.”

unsupported CPU installed

However when I pressed F2 it carries on booting, and I also can select other boot options as well, such as entering the BIOS. The Q6600 was also seen by Windows 10.

Q6600 CPU Phoenix AwardBIOS

I’m using 4GB of memory, and the dx2420 uses DDR2. I never run mismatched RAM, and below are two types of memory sticks I have used in this computer:

  • Hyundai Electrics HYMP125U64CP8-S6 DDR2 PC2-6400 800MHz
  • Nanya Technology NT2GT64U8HD0BY-AD DDR2 PC2-6400 800Mhz

There are only two slots available on the motherboard.

inside a dx2420 case

Power Supply Unit (PSU)
As mentioned, I own two of these computers and each arrived second-hand with a 300W PSU. When a PSU died, I didn’t have to buy a bespoke PSU.

Should you buy a dx2420?
Due to the CPU and RAM limitations, if you’re looking to buy a dx2420, perhaps reconsider and look at other computers, such as a Dell Optiplex 380.

The dx2420 upgrade options are limited and I often see them being sold for what I think is too much money, with better alternatives available for similar pricing. If you see one for an amazing deal, then you need to consider whether it can/could meet your needs.

Do you already own a dx2420?
If you already have a dx2420 and you are running Microsoft Windows Vista, then you could look at other operating systems, such as Linux Mint, Recalbox and Windows 7 or 10.

You might be using a dx2420 without a graphics card and not only will some graphics cards help with performance, but also provide DVI and HDMI connections. I use the ATI Radeon HD 5450 PCIe graphics card.

If somebody gave me a dx2420 for free or I saw an incredible deal, at the moment I would consider buying another one of these computers for low performance use.

Out of the two dx2420 computers I have purchased, I now only have one with the original motherboard. I intend to carry on using the computer. I’ve used the dx2420 for both personal and work use.

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23 days ago

I need help, I also own the DX2420, I bought the Intel 2 Quad Q9550 and it won’t boot saying it’s unsupported.