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Prime 95 reboots computer after 4 hours, por que?

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November 29, 2007 2:13:20 PM

I used to get rounding errors within an hour or two. Upped the voltage. After 4 hours of prime95 my comp will reboot, but rounding errors have stopped.

Running e6850 @ 3.7ghz on on a Gigabyte DS3R, 1.44v in bios (1.37 under load according to cpu-z, thats a lotta droop). Do you think my vdroop is doing this? RAM? (Kingston hyperx ddr800 running at 816, 5-5-5-15)

My PSU is:
http://www.newegg.com/Product/Product.asp?Item=N82E1681...


Anyone else have experience going from rounding errors to rebooting? Right now I strongly suspect it's still insufficient voltage due to vdroop, but I am not sure. I have heard RAM can cause rebooting more in prime95 and voltage is only rounding errors).

Help appreciated.
November 29, 2007 2:29:03 PM

Are you liquid cooling? If you are air cooling, then you are probably just pushing the thermal limits of the chip.
November 29, 2007 3:28:12 PM

What's your RAM Performance Enhance setting?

I got my roundoff errors under "Extreme" setting after 5 hours off Prime95 one time and a clean reboot after 2 hours (first time testing).

From what I've read when you use Extreme and overclock the system is stable for gaming, but not 100%.

The ram could also be to blame as it's over stock and most rams have issues over 800MHz at 1.8V.
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November 29, 2007 4:38:30 PM

I am guessing that this is repeatable - the PC reboots at around 4 hours while running Prime95. And I am guessing that if you run regular programs, everything works normally.

For stability testing, I run Prime95 for a full 24 hours.

Prime95 should run until you terminate it. What you are seeing is obviously some kind of instability. It could be thermal. It could also be power. I don't think that it is RAM. However, you can go into the BIOS, raise the RAM voltage to 2.1 volts, and relax the memory timings to 6-6-6-18. Then run Prime95 to check.

If it still reboots, look at the PSU. Besides the various power outputs, a PSU also sends a control signal called something like "PWROK" (gray wire, pin 8) to the motherboard. After you are up and running, if one of the outputs - probably the 12 volts - drops momentarily, you will lose the PWROK signal. This will force a reset/reboot.

According to the tiered PSU Listing:

http://www.tomswiki.com/page/Tiered+PSU+Listings

The Cooler Master PSU's are 4th tier at best. I looked at specs on the CM website. One of the things that I noticed was that the rated operating temperature is 0 - 40 deg. C. which means that the rated output (650 w) is probably at 25 deg. C (room temp). That means that, on the average, you will need to derate the output by 1 - 2% for every degree above 25 deg C. And that means that at 40 degrees - a not unreasonable operating temperature, your 650 watt PSU turns into something like a 500 watt PSU.

Try a better brand of PSU.
November 29, 2007 5:48:49 PM

Thanks for the info.

@thanatos: I'm aircooled, but I'm only a 60C, so I don't think the chip is getting too hot.

@Andrius: So you're saying if I want a stable system do NOT use extreme setting?


@jsc = Yes, it is repeatable. Doesn't happen at all during stock voltages running prime95.

I'll try the RAM first and if that does nothing, I guess I'll have to reduce my OC. I don't have enough money to spit out another 100+ dollars for an overclock that really won't have any effect on what I mainly do (gaming).
November 29, 2007 10:04:22 PM

EricVPI said:
Thanks for the info.
@Andrius: So you're saying if I want a stable system do NOT use extreme setting?

I'll try the RAM first and if that does nothing, I guess I'll have to reduce my OC. I don't have enough money to spit out another 100+ dollars for an overclock that really won't have any effect on what I mainly do (gaming).


Yes.
When overclocking the Ram Performance Enhance "Extreme" Setting is useless.
(I think I read something about it in the GA-P35-DQ6 Review on www.anandtech.com, but not sure).
It also doesn't work for me so I was googling it and found close to nothing on it.

The board you are using doesn't have to good power components as it's one of the cheap models.
November 29, 2007 10:26:05 PM

reduced fsb to 400, everything stable now


either the ram can't handle 818 over 800 mhz...or..uh, dunno.
!