Sudden stability issues with any i5-750 overclocking

tuxmytty

tuxmytty

tuxmytty

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Joined
26 Dec 2010
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14
I posted this in support, but just in case it takes a while for a response I'm hoping someone from the community might be able to offer some advice.

I bought a system in separates a few months ago which was stable with a conservative CPU overclock to 3.5ghz and memory to 1600mhz for several weeks, after which it intermittently wouldn't pass POST without the settings being reset in the BIOS.

And even on resetting everything to optimised defaults it would take several reboots and cmos clears to boot properly.

The main components are:

Intel Core i5 760 2.80GHz (Lynnfield) (Socket LGA1156)
Gigabyte GA-P55-USB3 Intel P55 (Socket 1156) DDR3 Motherboard
Corsair Hydro H50-1 High-Performance CPU Watercooler (Socket LGA77511561366AM2AM3)
Corsair CX 600W ATX Power Supply (CMPSU-600CXUK)
£37.99 x 1 - Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz Dual Channel Kit (CMX4GX3M2A1600C9)


It's now currently booting with default settings and will go at least one pass of memtest without errors on both memory sticks (previously one of the ram sticks only was showing errors on an overclock to 3ghz).

However, now if I try to overclock the memory to anything over 1333mhz (e.g. 1340 with a base clock of 134mhz) the system won't pass POST.

I can increase the block frequency to 166 with a cpu multiplier of 21 while setting the memory multiplier to 8 so that I have a stable CPU overclock to 3.5ghz and memory frequency of 1333mhz.

However, as soon as I try to increase the memory frequency over 1333mhz the system immediately powers off and reboots until the settings are returned to default. E.g. it now won't boot even with a cpu multiplier of 21, memory multiplier of 10 and block frequency of 134, giving a memory of oc of 1340mhz.

Could you offer some advice on the best way to diagnose the issue or should I just assume that the memory sticks are faulty and fill out an RMA?

I've tinkered a lot with the memory and voltage settings today to no avail.

This is what I currently have:

CPU:
Intel Turbo boost: disabled
cores : all
c1e: disabled
c3/c6,cpu thermal monitor, cpu eist, bi-directional prochot : auto

Memory
Performance enhance : disabled
dram timing selectable : auto

Voltage:
LLC : enabled
CPU Vcore : 1.25
QPI/VTT: 1.1
PCH/CPU PLL : auto
dram: 1.64 (have increased this to 1.66, as the ram has 1.65v on the sticker and decreased to stock 1.5v without any positive effect on stability).
Rest on auto
 
Sounds very much like dodgy RAM. Have you tried with one stick at a time? If it works with one but not the other then you've proved it.
 
Yeah, it would overclock with memtest errors on one, but now neither will oc.

Currently half way through the second pass of memtest with no errors on stock 1333mhz for memory.
 
Weirder...it's now booting with cpu at 3.5ghz (22 x 160) and memory running at 1600mhz.
Idle temp 37c.

I'll hold off to see how long it's stable (and run memtest again at some point). Please don't close the thread for now.

Cheers.
 
Agh...

It was stable with the settings above for just over a week and now won't POST without going to CMOS setup again even on resetting the settings to optimised defaults.

Do you think I should just assume that the memory is faulty and RMA it?
 
random...two bios updates and some fannying about to achieve finally the same settings and it passes POST.

Is this a normal experience? :S
 
OK. Is that RAM good for overclocking (I notice you have the same in your sig).

I guess, I could buy another couple of sticks and run with those while the suspected faulty ones are with OC.
 
My ram isn't overclocked, it's running at 1600, and complely stable at that. Works well with the CPU at 4GHz :D

I'm not guaranteeing your memory is faulty, but it would seem to be the prime suspect, due to the Memtest errors, and refusal to run at it's rated speed. If it was ok, you wouldn't be having all these stability problems. It's always possible it's motherboard or something else entirely though.
 
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