K8T Neo-FIS2R with Athlon 64 4000+ mobile CPU

Question

Doing some research on the net, I found out recently that the older mobile CPUs differ from desktop ones just by the lack of a heat spreader on top of the core. And I read up about many successful updates from ppl using the mobile CPU on the desktop socket 754 boards. This is for my 2nd system listed in my sig below - the  K8T Neo-FIS2R. I found a pretty good deal on the Newark CPU AMN4000BKX5BU recently (4000+). I took my existing 3000+ CPU out and I separated the heat-spreader from it. Underneath it's almost identical, except the core is a few mm larger than the mobile CPU. I mounted the heat spreader on the 4000+ CPU and made sure the core has good contact with the heat-spreader (checked the thermal paste imprint). Mounted the CPU in and the board powers on but doesn't POST. I then put my 3000+ in and works just fine. I repeated this 3 times, and just couldn't get the 4000+ to be recognized by the mobo. I thought the CPU may be bad, but it comes from a good source, so even though it's still a possibility, I started doing more research. And then I realized that I forgot to change the core voltage in BIOS from 1.5 to AUTO. The mobile CPU is rated for 1.35v. Do you think this is what affected it? Or is it because I'm on BIOS v.1.9 ? Latest BIOS is 7.1, but all versions passed 1.9 only introduced compatibility with Sempron CPUs (which I'm not using) and it limited DDR recognition to 333 only. I'm using DDR400 which is running well at 200MHz. All higher BIOS levels don't allow to run it in stock speed at higher than 166MHz. So that's why I wanted to keep the v.1.9.
Any ideas why the 4000+ CPU wouldn't be recognized by this board?
Thanks in advance!

Answer 1

I'm making some headway, but in effect, I temporarily hindered this system more than it was I got the CPU to finally work, but it only recognizes 1/4 of the memory I used to have... here are the details:
I upgraded BIOS to the latest 7.1 and the installed 4000+ CPU didn't allow the system to POST neither. I then cleared the CMOS and just for good measure removed 1 of my memory sticks (I had 2x1GB, as listed in my sig for the lower system). Then the old faithful came to life again After making more test I noticed that no matter what I do, whether I use DDR400 or DDR333 sticks (I also have those in 2x1GB), the only way it works is with a single stick in DIMM1. In manual, the configurations show that that memory can be inserted in different DIMM sockets, not necessarily the 1st one, but in my case, no other setup works than a single stick in DIMM1. As I mentioned earlier, BIOS versions above 1.9 (I checked them all in the past) don't allow DDR400 to run at 200MHz, but only at 166. Also, ver.7.1 reports CPU temperature incorrectly, about 10 degrees Celcius lower than it actually is. I actually noticed that in the past with my other CPU, too. Since nothing else could be accomplished here, I decided to go back to BIOS v.1.9. But the situation relating to RAM didn't change. It still only functions fine with a single stick in DIMM1.
I also tried resetting CMOS several times at different occasions, and when reset in ver.7.1 it would POST with 2 sticks of RAM in, but after loading BIOS settings, it would work fine (only as far as POSTs, because I never booted to OS during these tests) and would restart fine as long as it wasn't completely shut down. Once it was shut down, it wouldn't POST again.
In ver.7.1, the CPU was recognized by BIOS correctly as 4000+, however back at ver.1.9 BIOS recognizes it as 4200+ (something that doesn't exist for socket 754, AFAIK). However, the DDR400 is again working at 200MHz and the CPU core temp is reported correctly.
In ver.1.9 the CPU voltage when set to AUTO would run at about 0.9v, which might've been causing no POSTs until CMOS was reset. I manually lowered it to the minimal setting possible of 1.4v. It is rated at 1.35v and now is reported to run at 1.38v and still much cooler than my older desktop CPU 3000+. From what I read, AMD was doing binning on the mobile athlons, so I'm sure all of them can work fine even at 1.5v or higher, if needed.
Anyway, I temporarily gave up and decided to wait for some golden thoughts from you guys (or MSI Support, whom I also contacted about this, but it'll be a miracle if they respond with some help). Then I booted up into Windows, and even though CPU-Z recognizes the single stick of 1GB RAM I left there, Windows only reports it as 512MB. Also, CPU-Z reports the CPU in one spot as 4000+ and then in another (a little below) as 4200+. I guess the multiplier of x13 causes the confusion? Could that also be the reason for not recognizing more memory? I also tried lowering the HT Link in BIOS to 200 and 600MHz and that didn't help as far as allowing to use the 2nd stick of RAM. Please check the below screenshots for more details.
Thanks