With the trend of integration of Northbridge inside the CPU, one of questions that fall into place is what happens with the CPU if memory decides to give up the ghost. In the past, it wasn’t a rare thing to see memory modules driving the motherboard to the ground as well, and it was always an open question what will happen with the memory controller inside the CPU. Intel even went far to state that the company won’t warranty the Core i7 CPUs that have DDR3 modules with more than 1.65V voltage. Well, sadly, I got my answer earlier today.
System consisted out of AMD Phenom X4 9950, ASUS M3A78-T motherboard and 2x1GB GeIL DDR2-1066 4-4-4-12-1T memory. That memory worked either at these specs, or you could push it down to 3-3-3-7-1T on DDR2-800 and quite frankly, was the best memory I ever tested. These two year old memory sticks worked flawlessly in Intel Core 2 Extreme QX6700 and EVGA 680i motherboard, but paired with Phenom 9950, they decided to give up the ghost after two months.
Modules died without any spectacular event happening – shut the computer down, turned it back on a day later and the system refused to POST. After typical debug session (clear CMOS, replace memory, replace the CPU) it turned out that the memory died, thus I replaced it with alternative DDR2 modules and turned the computer back on.
What I was greeted was nothing nice, Phenom X4 9950 recognizing just one core and system crashed at boot. It turns out that memory doesn’t want to work in 128-bit “gangbanged” mode, thus we enabled the single-channel 64-bit ungangbanged mode.
I managed to get four cores working, but multi-threading capability just wasn’t there. Loading two applications would crash the system, and while single-threaded games worked, multi-threaded games such as Call of Duty or Far Cry would cause a BSOD. After replacing the CPU, system is working again 100% stable, but Phenom X4 9950 is a gonner. Thus, if you plan to use old DDR3 memory in your future Phenom II or Core I7 build, be careful what modules are you putting in the system. Both 1st Gen DDR2 and DDR3 modules came with high-voltage settings even written in SPD chip, so the newer CPUs might not like those settings.
Anyways, I can trash and recycle lowest-latency modules I ever had, and they’re sadly joined by a scorching hot 140W-eating Phenom X4 9950. Damn.