Increasing my CPU Ratio decreases my GFlops... Why?

[Bolide]

Hello all, have a weird issue that I'm hoping to get some direction on. Just got a new i5 4670K (Haswell) and an Asus Z87 Pro. Everything works great at stock levels, pulling about 90 GFlops on an average iteration of Intel burn consistently and can run at least 8 hours without crashing.

Here's the weird issue. Decided to start overclocking it so I pushed the Turbo CPU Ratio (my board doesn't give me an option to increase the regular CPU ratio, only the turbo) from 36 to 42 and upped my core voltage to 1.2 as has been advised on several i5 Haswell overclocking guides. Windows boots fine and the first iteration of Intel Burn yielded 100 GFlops which I was pretty happy about. Then the next one gave me 95, then 89, steadily decreasing until I was in the upper 70's. I was watching CPU-Z and my CPU frequency was fluctuating rapidly between 2GHz and 4.2 GHz where as the stock settings had my CPU at a pretty constant 3.6 GHz during Intel Burn.

I lowered my Turbo ratio to 40 and disabled Speed Step which I realized I had forgotten to do and realized that speed step may have been the culprit. I also made sure that my board was set for performance mode (vs power saving to avoid any sort of power throttling).

Unfortunately this did not resolve the issue. Any thoughts? I'm about to log off for the night but any advice or questions would be appreciated greatly and I'll be back on in the afternoon to check this thread.

Thanks!

 

[Buzz247]

first - check settings against this as a start:
http://www.tomshardware.com/forum/id-1722630/intel-god-quick-dirty-guide-4ghz-haswell.html

second - that reeks of voltage or thermal throttling. a lot of folks forget to keep decent airflow over vrm heatsinks when they overclock. If you don't already, I would be using hwmonitor or real temp to get an idea of temps in system. It is possible your cpu bus ring isn't providing high enough voltage either. Hence why i suggested starting with the guide.

 

[schmuckley]

Probably because of "turbo"
I'm not familiar with that chipset yet;I've been hearing there's a lot of different settings.
Try this: http://www.xtremesystems.org/forums/showthread.php?286345-ASUS-Z87-Motherboards-Overview-Guides-and-Official-Support

 

[Bolide]

Hello all, have a weird issue that I'm hoping to get some direction on. Just got a new i5 4670K (Haswell) and an Asus Z87 Pro. Everything works great at stock levels, pulling about 90 GFlops on an average iteration of Intel burn consistently and can run at least 8 hours without crashing.

Here's the weird issue. Decided to start overclocking it so I pushed the Turbo CPU Ratio (my board doesn't give me an option to increase the regular CPU ratio, only the turbo) from 36 to 42 and upped my core voltage to 1.2 as has been advised on several i5 Haswell overclocking guides. Windows boots fine and the first iteration of Intel Burn yielded 100 GFlops which I was pretty happy about. Then the next one gave me 95, then 89, steadily decreasing until I was in the upper 70's. I was watching CPU-Z and my CPU frequency was fluctuating rapidly between 2GHz and 4.2 GHz where as the stock settings had my CPU at a pretty constant 3.6 GHz during Intel Burn.

I lowered my Turbo ratio to 40 and disabled Speed Step which I realized I had forgotten to do and realized that speed step may have been the culprit. I also made sure that my board was set for performance mode (vs power saving to avoid any sort of power throttling).

Unfortunately this did not resolve the issue. Any thoughts? I'm about to log off for the night but any advice or questions would be appreciated greatly and I'll be back on in the afternoon to check this thread.

Thanks!

first - check settings against this as a start:
http://www.tomshardware.com/forum/id-1722630/intel-god-quick-dirty-guide-4ghz-haswell.html

second - that reeks of voltage or thermal throttling. a lot of folks forget to keep decent airflow over vrm heatsinks when they overclock. If you don't already, I would be using hwmonitor or real temp to get an idea of temps in system. It is possible your cpu bus ring isn't providing high enough voltage either. Hence why i suggested starting with the guide.

Well I checked out that guide you posted and I did everything it said down to the letter and the issue still occurs where it bounces between around 2GHz and whatever maximum frequency the multiplier I set will allow. The odd thing is, if I leave it at default (multiplier is 38) everything stays solid with little to no variance in clock speed over time. But if I raise my multiplier by even 1 (38 -> 39) it starts happening, even with my voltages bumped up to the higher end of what the guide specifies and with all unnecessary features (such as speed step) disabled.

I actually have a fair bit of overclocking experience from back in the Core 2 days so even though this is a bit different I've noticed that so far a lot of things still seem familiar/understandable to me which is why this issue is confusing me so badly.

Also, when I look at real temp, my temperatures fluctuate wildly between 70 degrees C and 99 degrees C but when I load up my BIOS after extensive testing in Intel Burn, it's around 70-75 degrees C so I don't really think that it's a temperature thing but I could be wrong there as well.

Any more advice would be greatly appreciated. Thanks ahead of time!

 

[Buzz247]

That is thermal throttling 10 to 1. What cpu cooler? What case? How are fans setup? Wire management? Vrm heatsinks clear and air getting to them?

 

[Bolide]

That is thermal throttling 10 to 1. What cpu cooler? What case? How are fans setup? Wire management? Vrm heatsinks clear and air getting to them?

I am currently on the stock CPU cooler

My case is http://www.newegg.com/Product/Product.aspx?Item=N82E16811119197 (Cooler Master HAF 922)

My fans are currently just the fans that just came with the case so there's one 200mm front, one 120mm rear, one 200mm top, then of course the little bit of air flow the PSU provides. There is also a ventilated side where I could install a 200mm side fan

No extensive cable management but I do my best not to have wires all over the place and I always do my best to keep them clear of the CPU. The PSU is also modular so I don't have any cables that I don't need plugged in.

I am currently under the impression that you seem to be more experienced with this than me, however I find it odd that everything runs fine at a Ratio of 38 but if I up it to 39 all of a sudden things go crazy. Could this really be thermal throttling?

One more note that you may be interested in... I decided to ditch the idea of playing with my ratios temporarily and decided to just disable Turbo Boost and turn up my BCLOCK a bit to achieve a 4GHz OC. The exact same issue occurred using that OC method as well.

Thanks again for the help so far!

 

[Buzz247]

Dear gods please stop! Do not oc on a stock cooler! They are designed to handle 70-80w of heat. Not 130w generated by oc. Yes this is absolutely thermal throttling. Get an aftermarket cooler like thermalright silver arrow, or coolermaster 212 evo before going any further or you risk damage

 

[Bolide]

Dear gods please stop! Do not oc on a stock cooler! They are designed to handle 70-80w of heat. Not 130w generated by oc. Yes this is absolutely thermal throttling. Get an aftermarket cooler like thermalright silver arrow, or coolermaster 212 evo before going any further or you risk damage

Just ordered the Evo. My last build, like I briefly mentioned, was a Q9400 that I pushed up to 3.4 GHz from 2.6 on air with stock cooling no problem so I just assumed I'd be fine again with stock cooling. It didn't even run hot, I think it was running at around 70 degrees C under full load. But looks like I assumed wrong here.

Thanks again, I'll try to remember to poke my head back in here once it's installed and let you know how it went

 

[Buzz247]

Please do! Look forward to it

Psst.... did u get some good thermal grease?

 

[Bolide]

Please do! Look forward to it

Psst.... did u get some good thermal grease?

Yeah, THAT's something I NEVER skimp out, I got some Arctic Silver 5