TH has posted a follow-up article to the one in which they toasted an Asrock P55 Pro MB with 1.40Vcore.
http://www.tomshardware.com/reviews/p55-motherboard-overclock,2460.html
In summary:
"Our previous page shows that our processor consumed over 200W when fully overclocked at 1.45V, while ASRock’s engineer told us the P55 Pro’s voltage regulator is designed to sustain 150W. While many might suspect a hardware change might be required, ASRock already had a hardware solution designed into its motherboard. It turns out that the motherboard already had over-current protection built-in, and ASRock had simply neglected it in the BIOS, believing that average overclockers wouldn't need it. A BIOS update to version 1.80 was the sole requirement to fix the P55 Pro. We were first pleased to find that a simple BIOS update allowed us to fully test the P55 Pro’s overclocking capability without a single sign of fatigue to the board. It completed several hours of eight-thread Prime95 stress testing at 1.35V, and dutifully shut off when we tried to apply even more stress through increased voltage and clock speed.
It has been our contention that no motherboard used for overclocking should be able to push enough energy through the CPU voltage regulator to damage it, because any motherboard that includes overclock settings should also include over-current protection. We understand that cheaper boards use lower-capacity voltage regulators, but lower capacity simply adds to the need for such protection. Any motherboard too cheaply made to include over-current protection shouldn’t even have manual voltage control, but should instead be marketed towards the non-overclocking whitebox market.
ASRock proved itself by using nothing more than a BIOS update to enable the over-current protection already included in P55 Pro. While leaving the feature disabled in previous BIOS revisions was a big mistake, redemption in the form of BIOS revision 1.80 is enough for us to have some faith in a board that can be pushed to 1.35V and 4.0 GHz with our Core i7-870 processor. Anyone who wants to use higher voltage to reach even greater clock speeds shouldn’t have a big problem choosing a higher-priced product. On this board, upper-range features such as dual eSATA ports, onboard Port 80 diagnostics display, onboard power and reset buttons, a rear-panel CLR_CMOS button, and IEEE-1394 FireWire now make the board a perfect fit for enthusiasts who prefer not to push their luck at high overclock settings."
How has Asrock proved itself with a bios that enables over-current protection? It's still a cheap-ass MB with the same cheap components that can not be oc'ed over 1.35Vcore. They should change the tech specs of this MB to include, "For those who prefer not to push their luck at high overclock settings". You maybe able to reach 4.0 GHz @1.35vcore with an i7-870, but I doubt you can do it with an i5-750 with this MB.
Bios V1.80 is not available on their site. They are now up to V2.00. V2.00 moved bios settings around and gives you more vdimm settings lower than 1.559V. This bios also causes CPUZ or Everest to not report core voltages.
I gave their bios Easy OC feature another try. It set the bios to:
3.8Ghz, 190, Vcore – 1.33125, Vdimm-1.615, VTT – 1.174 PCH – 1.100, PLL – 1.903, Ram 8-8-8-21 @570 Mhz
Speedstep – Enabled
Intel C-State – Enabled
C State package limit setting – Auto
changed SATA mode from AHCI to IDE
With Speedstep enabled when you boot into Win 7 you immediately get a hardware BSOD. These settings, with Speedstep disabled, also failed Prime95 Blend after 6 hours and LinX (all memory) after 3 minutes.
Asrock also has new Win 7 64bit versions of their OC Tuner and IES (Intelligent Energy Saver) programs, but to enable IES you have to enable Speedstep in the bios. IES only useful feature is that it's telling me my CPU @1.325V is consuming 82W idle, 91W full load.
Taking a cue from N7, I ran LinX (all memory) on my current 3.8 Ghz oc,(1.325Vcore bios, VTT-1.209V, PLL -1.903V, PCH -1.100V, Vdimm-1.559V) which was 12 hours Prime95 Small FFts and Blend stable. It failed after 5 minutes. I tried increasing the vcore up to 1.35V and then the other voltages but it still failed after 5 mintes. I can't get it stable at 3.8 ghz, could be the CPU, MB, ram, or the CPU/ram interface. I tested the ram with Memtest86+ at 760 MHZ, 1.559V, 9-9-9-24 for 6 hours with no errors.
I dropped down to 3.7 Ghz and same voltages. It failed LinX on the 47th run. I upped the vdimm to 1.603V and it passed 3-50 runs at all memory(94-98% mem usage, problem size 21166, 3435MB, 53 Gflops, 65C load), and Prime95 Blend for 12 hours (60C load). Even though LinX saves me hours of testing, I'm still going to use Prime95 Blend as my final test. Old habits die hard. Now let's see if I can lower my ram timings.
LinX, like Intel Burn Test, is Intel's Linpack with an easy to use GUI. The author suggests running it for 50 -100 runs at all memory. The latest version can be downloaded here:
http://www.xtremesystems.org/forums/showthread.php?t=201670
Final Answer:
I tried lowering my ram timings to 8-8-8-24, no go, failed LinX. So I'm stuck at 3.7Ghz, 1.325vcore bios, 1.601vdimm, VTT 1.203V, PCH 1.100V, PLL 1.903V, LinX full memory 50 runs and Prime95 Blend 12 hours stable.
Asrock P55 Pro, bios V2.00, i5-750 3.70 Ghz @1.325V bios, Cooler Master Hyper 212 Plus (2 fans) with TIM Consultants T-C Grease 0098, G.Skill Ripjaws 4GB (2 x 2GB) DDR3 1600 @ 740 Mhz 9-9-9-24, 1.6V, OCZ ModXStream Pro 700, MSI NX8800GT, Win 7 Ultimate 64bit