Q6600 failureclocking

MURDEROUS G · 27 Jun 2008 at 02:33

Just put together a Gigabyte P35-DS3P, Q6600 and 4GB OCZ DDR2 800MHz. Trying some fairly tame overclocks at the moment, and I don't seem to be able to get even a mild OC to remain stable. At 2.8GHz (400x7) with 1.4V vcore, the system falls over and dies within a few seconds of starting a Prime95 'In-place Large FFTs' or 'Blend' test. The RAM is unlinked and set to 2.0x, which should be OK, right? (I am relatively new to overclocking so apologies if I have neglected to mention something obvious)

After doing some searching for posts by other people who've had stability issues at such relatively low speeds, and reading this thread, I tried running a Prime95 'Small FFTs' test and that appears to be perfectly stable. What does this indicate?

Thanks in advance,
mg

mk17 · 27 Jun 2008 at 02:51

run small-ffts, with "Round-off Checking" on the Advanced menu, and make sure you've set ram volts (vDimm) to c.2.10v. 2.8GHz should be a given out-of-the-box for Q6600.

If you have 2*2GB ram, put them in alternating sockets, not neighbouring ones. if you have 4*1GB it doesn't matter.

Ideally run a full memtest at stock settings to make sure you're starting from a stable position. At intervals during your o/c hit small-fft's (or orthos) to ensure stability.

You really should be 8-hours Prime stable when you're finished - but opinions do vary, considerably - and heatedly

.

MURDEROUS G · 27 Jun 2008 at 03:53

Hi mk17,

Thanks for your reply.

mk17 said:
run small-ffts, with "Round-off Checking" on the Advanced menu, and make sure you've set ram volts (vDimm) to c.2.10v. 2.8GHz should be a given out-of-the-box for Q6600.

The DS3P has a 'DDR2 Overvoltage' option in the BIOS. Setting this to +0.3V should give vDimm 2.1V, right?

If you have 2*2GB ram, put them in alternating sockets, not neighbouring ones. if you have 4*1GB it doesn't matter.

Yep, that's how they're configured currently.

Ideally run a full memtest at stock settings to make sure you're starting from a stable position. At intervals during your o/c hit small-fft's (or orthos) to ensure stability.

I downloaded memtest86+, burned the ISO and am running it on the first of my two 2GB sticks now. Less than halfway through the first pass, it has encountered 83 errors. I guess we have identified the problem?

thegoonden · 27 Jun 2008 at 08:27

Not much to offer in way of help, beyond re-iterating checking timings and volts (watch out for the 1t/2t option, you can get away with 1t at CLOSE to the design speed probably, but bang on the right speed, you really need it set to 2t). Try also settting stupidly slack timings, just for the sake of science.
But I can confirm that your descibed symptoms absolutely point to RAM as the problem.

Trox · 27 Jun 2008 at 09:38

MURDEROUS G said:
I downloaded memtest86+, burned the ISO and am running it on the first of my two 2GB sticks now. Less than halfway through the first pass, it has encountered 83 errors. I guess we have identified the problem?

If you ran the memtest with default memory timings / volts and encountered this, then this is the problem. You need to set up an RMA to get the memory shipped back to the supplier.

I wouldnt bother slacking off the memory timings to get the sticks to work, if they don't work at the stated speeds then get them replaced.

MURDEROUS G · 27 Jun 2008 at 09:47

Trox said:
If you ran the memtest with default memory timings / volts and encountered this, then this is the problem. You need to set up an RMA to get the memory shipped back to the supplier.

I wouldnt bother slacking off the memory timings to get the sticks to work, if they don't work at the stated speeds then get them replaced.

I figured that too, but then I took a 1GB stick from an older machine, which I know is good, and memtested that too just as a control. Again, hundreds of errors per pass, and all the same error as before. I googled the error, and it seems to be a known false-positive issue with certain versions of the DS3 BIOS.

Anyway, long story short, I used Gigabyte's own Windows BIOS update utility to flash the BIOS to the most recent version to eliminate the false positives, and the BIOS update promptly failed. So now I have something rather more immediate to worry about than the RAM.