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Total lock up of system during prime95..temps were fine....

Last response: in CPUs
April 22, 2010 8:02:33 AM

Hi, I just recieved my Gigabyte GA-P55-UD3 board for my i7 build, (RMA'd crappy ASUS P7P55D-E LX...garbage) and it seems like
a very solid board for a budget p55 chipset. Anyway I got my i7 860 installed, a Corsair H50 cooler and once I had W7 and all drivers in,
I ran the sensor test on Real Temp, which booted up prime95 and proceeded to load/heat my cpu.
Everything looked fine, the temps were pretty amazing compared to the stock rubbish Intel gave me (sorry wasn't recording, but mid to high 40's and one core at 51'ish?)....I left the room for a moment and when I returned the whole desktop was frozen and unresponsive,
during the second test....!? Like I said, the temps looked fine as far as I can tell.

I have 4 gig of G.SKILL Trident 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL8D-4GBTD
Gigabyte GA-P55-UD3 MOBO, ( using XMP to get the 1600mhz at 8,8,8,24 timings as per what G skill told me )
Corsair H50 cooler, ANTEC 900 case and fans.
Is that Xtreme Memory Profile in effect an overclock? i'm kinda bummed by this as I thought I had built a solid system that I could maybe O.C at a later date.
Am I right in thinking that if it was a heat issue I would get a reboot or a BSOD??
Thanks in advance, and sorry for my noobness. :pt1cable: 
a b à CPUs
April 22, 2010 11:20:04 AM

With an i7 860, the XMP isn't a CPU OC. With an i5 750, XMP at 1600 starts to mess with bclk which is a CPU OC.

You can accomplish the same thing by hand. Set your memory multiplier to 12 and your timings to their rated 8, 8, 8, and 24. Also set the DRAM Voltage to whatever the RAM is rated at. Likely 1.5 V or 1.64V. Then try running Prime95 again. Stick around and keep an eye on your temps. Heat wouldn't necessarily crash it, it could throttle the machine which might lock it up. Double check all your H50 connections. Also, look in the system event log and see if it threw an error at the time of the lockup.

If you haven't run memtest86+ yet you should give that a run too. Setup your RAM and then let memtest86+ run over night to check for errors on the RAM. You can download the lastest version (4.0) to create a bootable CD here:
Related resources
April 22, 2010 12:44:09 PM


Thanks for the reply and advice. So I did what you said and set the RAM manually, the timings/voltage and multiplier. And I just successfully went through the
sensor test that Real Temp does with Prime95. No lock up!! I will run Memtest while I'm in bed too. As far as I can tell (at least at stock speeds anyway) this Corsair H50 is fricken amazing for 80 bones. here is a pic of my results.
a b à CPUs
April 22, 2010 1:52:34 PM

Wow, you never spiked past 46C. I don't know how long real temp stresses the CPU but that's really good. Thanks for posting the results.
April 22, 2010 8:43:42 PM

Memtest showed no errors. Cool, I'm buying another 2 sticks of these.