Had to stress test the 4790K after a long time

The last time I stress test day CPU was when I had the Maximus VII Gene board and the Noctua NH-U12S cooler. And it was with a low ambient temperature as well.

Fast forward to July of 2015 and we have a lot of changes. New case, meaning new motherboard and a new cooler. And Jul means, it's the summer. Sure, we have the A/C on, but the temps are around 26-27C, which is a couple of degrees higher than the previous months.

Wouldn't I have stress tested after all those hardware changes? I should have, but I didn't think it was necessary. For one, the stability of the overclock of Intel CPUs these days don't seem to be affected by the temperature. So the cooler or the lack of airflow inside the case shouldn't have made a difference. Then, Asus says that all of their Z97 Motherboards overclock exactly the same; only the feature set is different. More importantly, I didn't have the time to go through it again.

But yesterday, while I was transcoding a HD video in Handbrake, I got a BSODs. The dreaded "WHEA UNCORRECTABLE ERROR" error.

So the overclock wasn't stable after all. It was time for me to stability test the CPU. At least this time I had a starting point.

“4.5GHz @ 1.21V Vcore with everything else set to default”

That was where the CPU was at up until now.

But first, I wanted to make sure a stress testing tool would find the current overclock settings as unstable. I am not a fan of synthetic stress testing tools such as Prime 95 or AIDA64. Instead, I turned to Asus Realbench, which can be downloaded from here.

[Article] The ultimate stress test for Haswell CPUs - Prime 95 with AVX2/FMA3 support

Overclocking Haswell CPUs is a lot of work. Checking whether the overclock is stable or not is very time consuming. Some people go for a couple of hours of stress testing because most of the times that is enough to ensure that the CPU will run stably in every real world situation. But there are some people who cannot sleep if they know that one of their favorite stress testing apps didn't pass.

When it comes to stress testing applications, we are hearing a whole new story with Haswell. "This stress testing application is not certified for Haswell." Basically, that's what people say when they hear that you are using Prime 95 or LinX or OCCT. If by that they mean is that these applications don't  test every part of the CPU, the fine. But ironically, these apps can crash the CPU way quicker than those Certified applications. It makes one wonder, if Intel's CPUs don't work as they should. I mean, why cannot you simply run anything? Applications don't have to be certified for a CPU.

If it was the former, that is the application doesn't stress all the parts of the CPU, then the developers of Prime95 is finally fixing that. The current stable version, 27.9, supports up to AVX instructions. But no AVX 2 or FMA3 instructions. The developers have released an evaluation version of the upcoming version 28 which supports all these new instructions in Haswell. You can download it from THIS LINK.

Result?

Simply don't run the Small FFT test! On most setups, if you are above 1.20V, you'll be at instant throttling state. With 4.3GHz/1.24V, it would go to 97C within a couple of seconds. Well, I have my CPU fans at 1000RPM instead of the max 2400RPM, so it takes a couple of seconds to ramp up the fan speed. Maybe if I started at full fan speed, it might not hit that high. But still it will definitely be in the 90's,

But I don't stress test using Small FFT. I've found that almost always it is the in-place large FFT test that fails with my CPU. I ran it for a couple of hours, with each test running for only 3 minutes. The temps weren't that bad, however yesterday's weather was a tad cooler. 

Note: The Vcore written in the notepad is wrong. It should read 1.250V (1.264V in CPU-Z).

If you are running this, just be aware of the temps. There is no other stress test that can heat up the Haswell CPUs this much.

[Article] Haswell stress testing using Intel Extreme Tuning Utility(XTU)

I'm still trying to find the sweet spot for my Haswell CPU overclock. Prime95 has been failing on my in a weird way. Sometimes it would go for hours without failing. Sometimes even a slight voltage bump would cause it to crash instantly. If I go back to the settings that worked fine earlier, it would crash again.

Last night I decided that it was high time that I moved away from Prime95 and found something new that worked well with Haswell. I have tried AIDA64, but people have been complaining that even after passing it for 12Hrs, it would crash in games. I don't know if that is a good stress test either. Plus, you have to pay for it.

Some guy one Overclock forums recommended that he is using Intel's own stress testing utility called Intel Extreme Tuning Utility (a.k.a Intel XTU). People say that it fully supports the new AVX2 instructions, doesn't make the Vcore go out of control when the CPU is bombarded with AVX instructions and it also shows all the voltages and temps on the same screen (so that you don't have to run a separate monitoring utility (or utilities) as is the case with Prime95. AIDA64 also shows the voltages and temps while stress testing. However, XTU also allows you to overclock the CPU from itself. But I don't really like overclocking using software, especially when AISuite III is installed there and it can clash with other software.

So, I started a stress test in XTU last night and I ran it for 13hrs without a crash or error. However, I'm not confident that not failing XTU alone is a good indication of stability. So I am running a few hours' long H.264 transcode queue in HandBrake. If I can get through it without an error, then I guess I would be stable in everything that I do. I only stress tested the CPU portion. I skipped memory for now. If H.264 fails, I would test Memory as well. Otherwise I don't see why I need to do that because the clocks, timings and voltage is pretty standard for today.

The current overclock settings stands as follows.

• Core multiplier: 44x (sync all cores enabled)
• Vcore: 1.285V manually set in BIOS (should change to Adaptive later)
• Un-core multiplier: x39 (AUTO)
• Un-core voltage: 1.15V (AUTO)
• RAM speed: 1600MHz (XMP)
• RAM timings: 9/9/9/24/2T (XMP)
• RAM voltage: 1.50V (XMP)
• Input Voltage: 1.75V (AUTO)
• Extreme Tweaking: Disabled
• EPU Power Saving Mode: Disabled
• Everything else: AUTO

※This is on hte Asus Maximus VI Hero board with BIOS ver.711.

Here's proof.

Note: 
Time remaining says 10hrs 58min because I set it to 24hr stress test. Deduct that from 24hrs, and you get 13hrs 2min. 

[Article] Checking if your CPU overclock is stable

The most fun part of upgrading the CPU is overclocking. Of course, it is purely based on luck. You might get a CPU that can overclock wonderfully with low volts and low temps. And you might get a total piece of junk that needs a lot of volts and doesn’t overclock well. (I usually get that 2nd type of CPUs). They say it is silicon lottery. It’s a gambling man!

Temperature is your biggest enemy. In fact, when it comes to Haswell, temperature is your only enemy. To push the clocks higher, you need to up the volts up and that causes temperature to rise exponentially. Most people will have to max out at 4.2GHz on Haswell because of the heat. It’s mostly because of Intel’s crappy work using thermal paste in between the die and the heat spreader but there are other reasons too. Looks like they don’t want the enthusiasts to play with their silicon. Intel’s being naughty.

Say you have a good cooling solution and a good chip. Seeing those scores go up is nice and all, but making sure that your CPU is stable is very time consuming and pain in the butt.

But it depends. You can cheat a bit out of it if you want. You can either look for absolute stability or real-world stability. Failing in Prime95 doesn’t necessarily mean that you’ll ever get a crash (i.e. BSOD) with anything that you would normally do. I am more towards the absolute stability, but I don’t want to stress test for 24hrs in Prime95 with these summer heat.

Ironically, people have found out that sometimes even though Prime95 or any other popular stress testing app suggests that you have rock solid stability, you get crashes in games. So passing these stress tests doesn’t mean your are absolutely stable either.

So stability in my book means a combination of synthetic and real world tests as follows.

1. Prime95 v27.9 Blend – no errors or BSODs for 6hrs
2. Crysis 3 and/or Battlefield 3 – no crashes for 2hrs
3. Handbrake H.264 encoding (one pass) – no crashes for 2hrs
4. Asus Realbench – no errors or BSODs for 6hrs
5. AIDA64 – no errors or BSODs for 6hrs
6. Intel Burn Test: very high stress level – no errors or BSODs for 10 passes

If you can pass all these, then your overclock is stable. Out of all those, Prime95 is the most stressful. All others can pass, but Prime95 can fail with a higher chance. Most people will just run Intel Burn Test and say that their CPU is stable. But that alone is not good enough. Sure, you can say it is almost stable. I’ve been able to pass Intel Burn Test at 4.3GHz/1.22V but Prime95 would fail within seconds. Prime95 needed 1.24V to go on for 6hrs without a crash.

Ultimately, it is your choice. It’s your CPU, it’s your money paid, and it is you who use it. What if you can clock your CPU to 4.5GHz and get no BSOD and crash with the stuff you do with your PC and it fails all those synthetic stress tests? There is no harm clocking it up to 4.5GHz in that case.

My 4.5GHz overclock on 2600K has become unstable!

It's been a while since I tested for stability of my CPU's 4.5GHz overclock. I ran the blend test of Prime95 of more than 6hrs back then and I felt that was sufficient. However, PC has been giving random lockups in the past couple of months and I didn't want to accept that the reason for this instability was because my overclock wasn't stable enough. For some reason, it was so hard to find the settings that made my PC stable, and I didn’t want to go through all that again. It could be because I wanted to both overclock and save power at the same time. That's not something that's easy to achieve, obviously. Or it could be because the motherboard is not the best when it comes to overclocking. Or it can even be that this CPU is a bad clocker. Or I could have been doing something wrong in the first place.

Anyways, the reason for the recent instability could be due to many reasons. The first one could be because the last time I checked for stability, I didn't use a version of Prime95 that supported AVX instructions. Then, I did a couple of UEFI updates and maybe I needed to change “some values” to make the CPU stable under the firmware that I'm using currently. Or it could well be a problem with the power supply or motherboard or memory.

 

Want to overclock your CPU? Here are some tips to make it stable.

Remember those days when overclocking the CPU was considered dangerous and only a few people would even attempt it, and those people were treated like gods? Not anymore. Anyone can overclock their CPU if the CPU is overclockable and necessary hardware is available. Getting a modest overclock is easy, but if you are trying to squeeze all that extra juice from your CPU, you might need more than just luck.

Overclocking is not dangerous if properly done. Know your limits and obey by those limits. For example, don't insert a lot of volts to the CPU because it will damage the CPU. Keep it within the manufacturer recommended/commonly accepted volts for your particular CPU. Also be wary of the temps of the CPU as well as other components like VRM heat sinks of the motherboard.

Here are some tips.

1) Prepare a separate environment for overclocking if possible. If you have a spare drive lying around, install a free copy of Windows in it and don't install anything else - not even Windows updates or driver updates. Why this is important is because when your OS crashes while stress testing because your overclock is not stable, it can corrupt the files and settings and that alone can give a BSOD when you stress test with different settings the net time. You might think the CPU is unstable, but in reality it could be a corrupted driver or corrupted software that is running in the background.

2) Stress test for a couple of hours at stock settings. This will rule out any issues that might be present in the original hardware. No point trying to overclocking broken hardware. You'll only waste your "precious" time. Running Prime95's blend test should do the trick.

3) Don't overclock your RAM at the same time. Overclock only one component at a time, otherwise you won't know the culprit of the instability if you discover any. Overclocking RAM doesn't give any tangible benefits anyways. You will get better performance by overclocking the CPU. So, if you have high speed RAM (i.e. faster than 1600MHz), I would suggest that you drop the speed to 1600MHz CL9 timings. That would rule out the memory being the culprit of a crash. This is not needed, but just to be sure

4) Make a target. The target should not be in terms of clock speed, but in terms of max CPU temperature or max Vcore, whichever is reached first. For example, max Vcore = 1.4V and max CPU Temp = 85C. First, try Vcore = 1.4V at stock clock speed and run a stress test while monitoring CPU temperature. If you are below 85C, then you can simply try increasing the CPU clock speed. If you hit 85C, then stop stress testing and lower the CPU Vcore until your max temps are below 85C.

However, please note that when you increase the clock speed, the temps would increase a bit more even without increasing the Vcore. So try to stop about 5C below your suggested max CPU temps (i.e. 80C) to give some room for the temps to increase due to clock increase. Now that you have found your max voltage, it is time to increase the clock speed.

5) Be patient. Don't try to rush out thing. If you know that the CPU model you have usually overclocks to, say, 4GHz undoubtedly (all the current generation CPUs do), that would be a good place to start. You don't have to start from the stock speeds. That's not necessary. However, only increase clock speeds one step at a time.

For example, when it comes to Intel, the only way to effectively increase the clock speed is by raising the multiplier. Increase the multiplier one step at a time. That means, if you were starting from 4GHz, which means the multiplier was at 40x, increase to 41x, then 42x and likewise. At each step, stress test for like 30 minutes of Prime95's blend test. That should be enough for the intermediate stress tests. Once you find the maximum overclock, stress test for 24hrs (at least 12hrs) to make sure that is completely stable. If the stress test fails while doing the extensive stress tests, you'll have to drop the multiplier by one level. Then it is 24hrs of stress testing again. (Overclocking takes times. Don't rush it.)

6) Now that you (hopefully) found out your max CPU clock, you can revert to the original RAM settings or even try to overclock it. Remember that when you overclock your RAM, you might have to increase the VTT (memory controller voltage) to make it stable.

7) If you want to overclock further and you were limited by temperature, it is time to invest in a better cooler.

8) If you are having some particular issues, such as crashes at idle, take a look at this thread.

Those were some common guidelines and all that they do is make your life easier, even though at first it might seem like time wasters (preparing a separate environment just for overclocking, for example).

There are more extensive instructions on the forums such as Overclock.net, Techpowerup.com and XtremeSystems.org so read the guides posted there, ask questions and participate. You will learn a lot by doing that.

Prime95 with AVX support for Stress Testing your Sandybridge or IvyBridge CPU

I discovered this recently. I’ve been using Prime 95 without AVX support for all this time. Prime 95 with AVX support is the bomb. Just compare the temperature difference between the following screenshots.

Note: Small FFT stress test was run for 5 minutes.

Without AVX (v26.6)