Stop 124 errors overclocking Haswell


Nov 14, 2008
Trying to oc my 4770k on a Asus Z87-A board with 16gigs of Crucial Ballistix Sport memory. Memtest ran for over 12 hours with no errors. Memory is good. I am running Prime95 in blend mode and it's crashing after not even 5 minutes. I have my multi set to 42 4200mhz and my voltage set manually to 1.200. My cpu cache ratio is set to 39. Everything else is set to default.

What could be causing the stop 124 errors? I am not doing a crazy overclock here. Please help as I'd like to get this stable at least at 4200mhz. Windows runs fine and I can play games no problem. Just when I start prime95 it bluescreens after 5-8 mins.

My heatsink is a CM 212 Evo and my cpu has been delidded. Temps are fine showing at 60-69c.

Thanks for the help.


Apr 17, 2009
1. Don't run Prime95 with Haswell CPUs. Use Aida64 instead,
2. 124 means that you vcore is too low.
3. If the CPU is stable in everyday use, what's the point is running stability test with unreasistic load?



Apr 17, 2009
Well, mine is currently running at 4.2GHz 1.2v. To get to 4.4GHz I need to set the voltage to 1.25 and for 4.5GHz >1.27. Does not even boot at 4.6GHz :)

In any case, if your system is stable while gaming and working with the usual software, there is no need to increase the voltage. As I said, stress testing puts unrealistic load on the chip.

How exactly did you run memtest, CD,USB Stick, or BIOS?

Are we talking Memtest86, or Memtest86+?

Memtest86+ has not been updated since January of 2011, and back then it could not guarantee testing 4G of memory and you are testing 16G, which means you memory could be producing errors in an untested section.

Which memory is tested?

As much as possible of the system memory is tested. Unfortunately memtest86+
can usually not test all of the memory. The reason for this is that todays
processors have become so complex that they require a small amount of memory
to keep accounting data of the processor state. If memtest were to write
over these areas the state of the processor becomes invalid and it's
behaviour unpredictable. Alas it is also impossible to relocate these areas
in the memory.

This means that a small area of your memory can not be tested by memtest. If
this part of the memory is defective you will know soon enough though as the
processor, or parts of the processor simply won't work correctly if this
part of your memory is defective. Do realize though that in very rare cases
memtest will show no errors even though the module is defective, not because
memtest can't detect the error, but because memtest can't test the area the
error is located in.
Some memory problems diagnosed may be due not to faulty memory, but to memory being run at a higher speed than it is capable of.
With those quotes of information provided, now lets see if we can determine the problem?

Please list the exact specifications of the Crucial memory modules you are running, brand, model #, timings, voltage?

Also list how you are running them in the BIOS, Auto, XMP, manual?

Is this a matched set of modules?


Lets hope not since you've delidded the one you have and tossed the 3 year warranty out the window.

Voltage does not always solve this problem it surely did not help the laptop guy that had no voltage adjustment capabilities to his CPU but received the same blue screen stop 124 error because he had added new memory modules!

This error covers hardware problems and can cover a numerous amount of reasons as to why it is happening, from overclocking, to drivers, to unstable memory, or running memory module speeds past the CPUs memory controllers capabilities, so it covers more than just CPU voltage, but can additionally be caused by memory voltage as well.

The Haswell memory controller was designed to run at either 1333mhz or 1600mhz, thus the reason I asked the OP for his exact memory specs and how he was running the modules in the BIOS.

Sometimes it's best to crawl before walking, the same applies to overclocking, find a solid stable base to begin with then overclock it, if the OP is attempting to run memory speeds above 1600mhz he could be creating his own stop 124 errors.

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