P55 and DDR3 1600 F3-12800CL7D

[Integrexman]

I5 750 (stock Cooler)
Gskill DDR3 1600 F3-12800CL7D-4GBRH
MSI P55M-GD45 (latest BIOS)

I noticed after enabling XMP in the BIOS so the memory will run at 7-7-7-24 that the CPU frequency went from 133 to 160 I guess to get 1600 for the memory. I turned the Multiplier down to 17 to get 160X17=2.72ghz for the CPU. When it posted I noticed it said 160X17 2.72Ghz then a couple of lines down it said something like "OS SYSTEM 3.2Ghz".

I ran a few tests and found that with XMP enabled (CPU-Z) I was getting 3.8Ghz on a single core at 100% and 3.2Ghz when all 4 cores were at 100%. I would get up to 80C and the VCore would hit 1.314.

With XMP turned off in the BIOS, (133X20=2.66) CPU=Z says 133X21=2.79(four cores at 100% 63C and 1.232 Vcore) and 133X24=3.2(single core 100%)

Can I manually change settings in the BIOS so the CPU is not overclocked to 3.2ghz (80C) (160X20) and the memory timing will be 7-7-7-24? Will this make the Memory any faster or will it only speed things up if I also overclock the CPU?

[GSKILL TECH]

You will need to manually configure BIOS settings, seems like something is fishy about the XMP Profile.

BCLK goes to 160 because the i5 750 processor only has a 10X memory multiplier.

Make the following changes in BIOS and everything should be working properly.

BCLK 160
CPU Multiplier 17X
Memory Frequency 1600
Memory timings 7-7-7-23
Memory Voltage 1.60V

Save and exit, everything should be fine afterwards. Keep me posted on the results.

Thank you
GSKILL SUPPORT

[Integrexman]

I set the following manually in the BIOS:

CPU Base Freq 160
CPU Multiplier 17
DRAM Freq 1600
Memory Timing 7-7-7-23
DRAM Voltage 1.6

When it posted again it said "OS SPEED:160X21=3.36"

CPU-Z confirmed that with 4 cores at 100% I had 160X21 and single core at 100% 160X24. This is exactly what happens when I enabled XMP. It seems to ignore the CPU's multiplier I set in the BIOS and use 21 and 24 all the time. I rebooted and looked in the BIOS and it still had the setting above.

I regenerated some toolpaths in my CAM software it took 8:45 minutes with the stock settings 133X21 and 133X24, with the above settings it took 7:15 minutes but core temp was at 80C at the end. It is a good application to test the i5 on because it switches between one and four threads a lot. CPU-Z showed the multiplier switching from 21-24 as expected. My core2duo 2.66(E7300) dual core took 14:45 minutes to regenerate the same toolpaths.

[Integrexman]

Is this a MSI BIOS limitation or are all i5 MB this way?

[Grnfinger]

disable turbo and your multi will stay consistant

[Integrexman]

I disabled Turbo Boost and the multiplier stays to what is set in the BIOS. Without turbo boost my CAM software is not as fast since it switches between 1 and 4 thread so often. It would be great if the BIOS let you decide what the turbo boost multiplier would be for 1,2 or 3 threads. When XMP is on or when I set things manually if I only have 1 thread it can run at 3.8ghz and stay under 60C but 4 threads then run at 3.3 and the CPU hits 80C.

It seems to me if you plan on buying an i5 and do not want to OC the CPU there is no point in spending the extra cash on faster memory. I should have just bought DDR3-1333.