P7p55D evo i5 750, DDR3 1600mhz hard freeze

Kia Ora from New Zealand

This is clint here. I've forever been having trouble stabilising my system with a 4bg kit of Kingston Hyper-X at the rated 1600mhz, 8-8-8-20 @1.65v using both xmp and manually setting the options.

Mobo: P7P55D evo
CPU: i5 750 @2.66 stock or 2.72 with xmp and blck = 160mhz
Ram: Kingston Hyper-X DDR3 1600mhz 8-8-8-20 @1.65v
GPU: Radeon HD5850
PSU: Enermax Liberty 650w modular
Antec 900 II
1TB Samsung Spinpoint F3
640Gb WD caviar blue
250Gb WD caviar black(I think)

One quick side question: When I use the xmp profile to set the memory at 1600mhz it raises the IMC to 1.6v(which appears as danger purple in the bios). I've read a few forums suggesting such a high IMC would degrade and fry the cpu in due time. Why in the world does xmp set such a high voltage!?

Symptoms of the Freeze: It's been a while since I tried using my ram at its rated frequency and timings that I paid extra for. Depending on my GPU (I had a 5770 in which the screen would go multi coloured and my headphones would scream at me) in either case, the image freezes during gaming and must be reset. BSOD happend with both cards. It seems the crashes are a little less intense with the 5850 as I have got a readable stop code ending in 050x or something which indicates ram or HDD problems (im pretty sure). I'm thinking ram becasue it only happens with 1600Mhz and it still happened when I didn't have the 1TB drive.

I've seen others with similar sounding problems all over the net but I'm wondering if anyone has a good solution or has a similar problem. I've tested with prime95 and results were sweet. the freezes seem to happen more in Call of Duty titles over any other games. I think it randomly crashes sitting on the desktop too.

I looked at this issue ages ago when I though it was GPU related and tried mucking with ATI tray and setting playing with the different clock down voltages.

I flashed the bios semi-recently and I think it's the latest revision.
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  1. Kia Ora

    Cheers for your choice as feedback. I was just about to finish a reply to this last night with my computer manually overclocked to what the XMP settings would be to get DDR3 1600 when it suddenly blue screened with a stop error ending in ...0001E
    Can anyone tell me what that might indicate? It was running quite fine the whole day, performing well in games but just crashed at the end of the day.

    I got it wrong about the xmp setting the IMC voltage to 1.6v, its set to 1.3v but if you reckon I could get away with 1.16875 i'll try that. The stock cooler on 1156 cpu's are rubbish so im getting 54 degrees C idle temp at 2.7ghz with 1600mhz ram. My idle temps with everything stock are low 30's. I think this is attributed to speed step and the fact that the voltage drops to as little as 0.86v. Just a side question: does anyone know what bios or motherboard feature causes the voltage to drop when idle. Is is C-states? I'd like to apply that to my DDR3 1600 profile along with speedstep to get lower temps when idle.

    Here is my bios setting for manual overclock to achieve xmp like results, any comments on tweaks I could make would be apprechiated:

    cpu target frequency: 2720mhz
    DRAM target frequency: 1600mhz
    cpu multiplier: 17
    extreme phase full power: auto (dont fully understand what this does)
    BLCK: 160mhz
    DRAM frequency: DDR3 1600mhz
    DRAM timings: 8-8-8-20 N1
    cpu voltage: auto (cpu z says 1.144v)
    IMC voltage: 1.3v
    DRAM voltage: 1.65 (my DIMMs are rated at 1.65 but is it worth trying them at 1.6?)
    cpu_pll: auto (1.8v)
    PCH voltage: auto
    Load Line Calibration: auto (would like to know more about this, I know what it does, it's just that there are so many conflicting opinions about it. Some think it disasterous in conjunction with speed step as the changing multipliers can cause voltage spikes or something and others say its fine)

    In the end i'm just keen to make my system stable at DDR3 1600mhz and keeping the heat down. I'll think about getting a new cooler. I'm looking at a zalman CNPS9900 (LED or NT) ill get NT if it is noticably better.
  2. Easy solution: don't run at 1600MHz. Run at 1333MHz and tighten timings, reduce voltages. All this effort will get you 0-5% improvement in framerates and might reduce the life of your chip.

    I think al the power saving settings need to be enabled for it to downclock/undervolt at idle.
  3. Cheers for your feedback.

    There's no option for Ai power savings. I'm pretty sure its usually on but if you raise the BLCK above a certian frequency some things are permanently de-activated.

    Good Idea. I might try getting some tight as timings. My PC is just a gaming rig and video editing suite so i guess I'd benefit from faster access times rather than throughput.

    I think the excess heat with XMP enabled is generated from a high IMC voltage.

  4. I've got my timings down to 7-7-6-17 N1 at 1333mhz
    I could probably get the t(RAS) down to 15 or lower.
    IMC is at 1.1685v and ram 1.6375v
    It's running stable as and still all the power saving features and turbo boost working so that's good.
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