Dual power plane

[PEZ123]

Yes, we're back to the old AM2/AM2+/AM3 days 🙂

I have an AMD, Phenom II X4 955 Black Edition 125w TDP C3-stepping CPU (HDZ955FBK4DGM).

I've been running it in an ASUS M3N78 AM2 motherboard for 2 weeks without problems, but today the PC died twice, and upon reebot, the PSU threw sparks and the PC died.

The M3N78 (http://www.asus.com/Motherboards/M3N78/HelpDesk_CPU/) has whitelisted CPUs with this multiplier and CPUs with 125 TDP, with the newest BIOS, but no C3 125 TDP CPUs.

From: http://www.amdzone.com/phpbb3/viewtopic.php?f=52&t=137458
""Some top-level AM3 processors (x945 125W, x955 125w and x965 140w/125w) require a special power supply feature, often called "dual power-plane". It's supported by default in all native AM3 mainboards, however not in most AM2+ motherboards, even those advertised as "AM3 optimized" or "AM3 ready"."

Please note that the description above is not entirely accurate. By design, the AM2r2 platform should support dual-plane. However, some early AM2r2 boards may not properly support dual-plane-only CPUs due to outdated BIOS they use."

Could this be due to lack of dual power plane? Or would the issue not show itself in such a way?

It ran fine for two weeks, always under a light office load, temps around 30-40 C and the cores underclocked to 800mhz most of the time. Hence the PSU should have been adequate. On the other hand, the PSU had been on for around 16hrs a day for 8 years with a 65w Athlon 64 x2 4200+. Then it's just a strange incidence that it would die 2 weeks after the CPU was replaced.

To sum it up, my question is this: If only the PSU is fried, should I just replace that, or in addition to that, find a CPU which is whitelisted for this board?

 

[PEZ123]

Hmm... on the Phenom II wiki-page, it says that if the mobo would only provide single plane power, the CPU would be locked to a x4 multiplier. But it has been running fine at 3200 mhz. A CPU-Z dump which I have taken earlier confirms this:

Power 0 19.50 W (Package)
Clock Speed 0 799.96 MHz (Core #0)
Clock Speed 1 799.96 MHz (Core #1)
Clock Speed 2 3199.83 MHz (Core #2)
Clock Speed 3 3199.83 MHz (Core #3)

 

[InvalidError]

The PSU "throwing sparks and dying" is completely unrelated to whatever may be going on with the motherboard or CPU. Get a better quality PSU (ex.: just about anything from Seasonic) and cross your fingers that the PSU is the only thing that died.

 

[PEZ123]

Yeah, I hope you are right (I've told my father not to turn the PC on again, if it shuts down a second time for no apparent reason, minutes after the first time...) and that the PSU was the only thing which died. Just strange that it would happen so close to a CPU-replacement. Therefore my concerns re the CPU.

Would you have any opinion on the PSUs? They are just a bit cheaper than the Seasonic S12II-430.

http://www.chieftec.com/power_GPE.html
http://www.antecindia.co.in/product.php?id=NzA0NDM1
http://www.corsair.com/se-fi/vs-seriestm-vs450-450-watt-power-supply-eu

The PC is running light work in Win 10, on-board gfx and a Samsung 840 Pro, so there's no real power hog but the CPU.

 

[InvalidError]

There isn't much info out there about Chieftec in general, the Corsair VS series are sub-par, that leaves the VP500C as my first pick assuming it is at least as good as the regular VP500 in North America.

 

[PEZ123]

The VP500C should have dual +12v rails, but is not 80+ rated, whereas the Seasonic seems to have it all.
You've convinced me. Thank you very much for the input.