Help updating BIOS

Hello!

My OS is Win7 ultimate 32-bit.
I have an Asus P5LD2-X/1333 motherboard. I used to have a Intel Pentium Dual-Core 1.80ghz. Today I installed a Intel Pentium Dual-Core 2.50ghz E5200. It's running just fine, without any software updates. However when starting the PC I get the following message:

Unknown CPU detected. Update BIOS to unleash it's full power.
Fress F1 to continue.

As I said, Windows runs just fine. But I feel like I should update the BIOS (or should I really?).

After 2 hours of failed attempts to update it, I find myself here. The update file i got from the Asus site is a .rom, so I can't run it with Windows.

So what have I done?
First I created a bootable flash drive with the .rom file on it using windows's tools (cmd > diskpart) as fat32. When trying to boot it (after I changed the boot order) I get a message saying "Remove any storage or media". When I use the BIOS's EZ Flash I get the following loop:

Checking floppy...
nothing found!
Checking CD...
nothing found!
etc etc

I tried the same, this time with ntfs - same results.

Then I did the same, this time making the flash drive bootable with Rufus. The results are mostly the same, but this time when I boot it, I get a flashing "_" at the bottom left of the screen. It stayed there for 6 minutes and I eventually lost patience. Should I have waited more?

Final note: I had been using a 2gb and a 4gb flash drive. Just now I've read that I have to use a flash drive with less than 1GB. The smallest I own is 1GB and it doesn't work.

At this point I am kind of frustrated. Any help will be greatly appreciated.
Thank you for your attention.

Bear in mind that if you screw up a BIOS update, it's very easy to turn your pc into a doorstop.

wasnotwas said:

Bear in mind that if you screw up a BIOS update, it's very easy to turn your pc into a doorstop.

I am aware of that. I've made a backup using Universal BIOS Backup ToolKit 2.0

Does the BIOS update specifically address the issue you are having? Checking this is standard practice before nay BIOS update. If it does not then it most likely won't make any difference and the update should not be done.

Well every time I start my PC up I get the F1 message, but upon hitting F1 Windows starts up as normal. Everything seems to run as it should and I'm noticing performance improvements. I wouldn't be surprised if updating the BIOS does nothing.

It's best if I leave it as it is, I think.

Also, in the BIOS I managed to turn off the F1 error display, so the PC just starts up without waiting me to press F1.