Puzzled.
 

To breathe a little more life into my middle aged computer which is a socket 939 AMD motherboard my son updated the bios to the latest version and then fitted an Opteron 175 dual processor. The odd thing is that sometimes the computer sees and runs both cores and sometimes only one. This has me baffled so any ideas anyone apart from reinstalling windows from scratch which I do not want to do.

Some programmes are only designed to run on one processor, some are coded to take advantage of both cores. Programmes written before dual core CPUs can't do much to make use of the 2nd core.

I know not all programmes can see or use two cores. What I mean is Windows itself varies on whether it can see one or two cores after bootup, ie whether they are available or not. Various diagnostic programmes like Si Software Sandra, HWiNFO32 and AMD's own programme agree with Windows as to whether I have two cores available or not. I assume the correct HAL must be loaded or two cores would never run??

Hi Mike - I'm a bit lost on this one, I think you are saying that after start up it is firing up sometimes as a single core machine and sometimes as a dual core? Having fired up in single core mode does it ever revert to dual core by itself - while running other things besides Windows?
Anyway - to start with I would check all connections - particularly on the new parts.

Yes Andy that is what I am saying. It stays in whatever mode it happens to be in until the next boot. The cpu/heatsink seem well down in position and I don't really feel like disturbing them and having to re thermal grease them.

Mike have you upgraded the fan(s) - sometimes a new hotter processor may do this as it overheats slightly, or does it go into single core mode from cold?

New fan and heat sink fitted (with paste) and, yes, it does go into single core mode from cold. CPU temp settles on 35c and is stable as is the system in whichever mode it happens to be in.

Sorry Mike I'm also puzzled - I will consult my oracle - my brother - a nerd who enjoys reading source code??!!!? He asks what power supply you have fitted?

Thanks Andy, will have a look tomorrow (28th) as thats the only way I know of finding out and am too tired tonight. Will let you know.

Well have had a look:
Tagan model no. TG420-U01
Lots of different figures in a grid then:
Max Power 400W & 28W
Total Power 420W

Thanks Mike - David says minimum power supply for an Opteron 175 dual should be 520W - this may explain why it sometimes starts and other times not. Looks like you may need a new power supply? He says as long as it is AMD approved 500-550W should cover it.
Hope this helps
Andy

Thanks Andy, I am sure that is it, makes sense. More expense!

Well fitted a Cool Master 520W PSU which can peak to 600W and guess what - no difference! At least the computer seems to boot into dual mode from a cold boot but always single mode from a restart. If I have to restart I just turn it right off, wait a few seconds and boot and it works. I will just have to live with it but thanks for your help Andy.