Latitude 6500 intermittent no boot, flashing num lock indicator

Ok, this machine is still doing the flashing numlock deal as outlined in the OP. I've again backed up the data to an external hd. What can I do to fix it?

As mentioned before, the flashing numlock is a possible processor failure according to the manual.

A new motherbord is $75-$85 on ebay, or a new mb with base is $96.
New Original Dell Latitude E6500 Laptop Motherboard La 4052P J331N 0J331N | eBay

How hard is the motherboard to replace? My machine has the lighted keyboard and adjustable brightness screen, both of which are important to me. A new motherboard should not affect these features?

 

I would check the System Logs in the BIOS as the first place to start. Power-on/restart the machine and tap the F2 key continuously until you are into the BIOS screen. Go to the system logs section of the menu tree (bottom) and check BIOS events. There should be an entry referring to processor failure (or whatever is causing the issue) in that log.

If it is the CPU, you should be able to pick up any Core 2 Duo chip off ebay for a very reasonable price. (this might be a good time to upgrade to T9800/T9900). I would replace the CPU only if that is the fix, rather than replace the entire mother board. That is a little more time consuming than just the CPU. Make sure you buy a decent thermal paste to apply to the new chip. There are tons of videos available on YOUTUBE that will walk you through the process if you've never done it before.

 

Ok thanks.

This is what I found under Bios Events.

5/22/13, 11:34:06, Post event = CPU, LED code = Flash-on-on

Five more events with the same stuff between 5/19 - 5/22.

 

Like this one maybe?

Intel Core 2 Duo T9900 3 06GHz 1066MHz 6M Slgee Dell M4400 M6400 E6500 E6400 | eBay

 

The T9900 is the fastest CPU supported by the E6500. You might as well max it out since you're replacing the cpu anyway. Good luck.