Figuring out Z370-I Bios settings for an i7-8700

[AWDSOME]

Hello ROG Forum!

Here's my first post! I just got the z370-i board and am building a new PC, the first new build that I have done in almost 10 years! It seems things have change just a bit since I last did a desktop build, and have some questions around this board setup with an i7-8700 that I have in it. I've been putting together an SFF build in a Dan SFX-A4 v2 case, and finally had enough parts together to build it and see if it boots up. Here's my build so far:

• CPU: Intel Core i7-8700
  
• CPU Cooler: LP53 Heatsink + Noctua A9x14 Fan + Thermal-Grizzly Kryonaut
  
• Delid: Rockit 88 Kit with Coollaboratory Liquid Ultra
  
• PSU: Corsair SF600 600W Supply with cables from Cablemod (cables on order, using stock mess at the moment)
  
• Motherboard: ASUS ROG STRIX z370i
  
• SSD: Samsung 960 EVO 500 GB M.2 NVMe
  
• Memory: G.Skill Trident Z RGB DDR4-3200 - F4-3200C14D-16GTZRX – 2x8GB Kit
  
• Case Fan: None at the moment!
  
• GPU: None at the moment!
  

I got Windows 10 installed with all the right drivers and utilities, and then ran some tests, which initially had me a bit concerned. I was questioning the delid when I ran some tests using the Intel Extreme Tuning Utility.... seems idle is around 36 C, but using the CPU Stress test at 5 min it peaked at 94 C, and the Memory Stress Test was worse at 100 C and continued to climb! I don't even have a GPU installed yet! Something was not right, and after looking at a couple forum posts here, figured out that MCE was causing the heat due to increased wattage and such (a new concept for me). Followed the instructions in this video to figure out where to disable it in the ASUS BIOS:

https://www.youtube.com/watch?v=zi-zU2p2ykc

The TDP "boosts" to 122W for a max 28 seconds according to the Intel Extreme Tuning Utility. During these periods of boost, I'm seeing all of the cores at 4.3 GHz instead of 4.6 GHz, which is what I would expect. The maximum temperature after running a few tests (CPU and Memory tests) show a running average of 76 deg C, and a max around 84 Deg C. So That makes me feel better about the delid and cooling solution I have in place. :cool:

A new question I have now is when it's not in this 122W boost period, it comes down to 65W TDP as expected, but the speed seen on the cores bounces around 3.83 GHz to 4.03 GHz. "Power Limit Throttling" is the reason that the Intel ETU is flagging. I did a bunch of tweaking/testing in the bios, as well as used the 5-way optimization in AI Suite 3 to see if I could get it to stay at 4.3 GHz. The 5-way config did seem a lot more stable, with temps holding at 98C. But that's still too high for my comfort, I'd really like to see no more than 85C. My thinking here initially was if the i7-8700 is rated for 4.3 GHz across all cores in "normal TDP operation", what could I have set incorrectly for not being able to sustain 4.3 GHz? I did some reading, and it seems as though Turbo boost may be temporary? So this leads to my couple of questions (sorry for the long back story):

• Is this the expected behavior of the Coffee Lake CPUs? Spending some time at 4.3 GHz and then reducing?
  
• Given I have no experience Overclocking, I would like to have XMP enabled and still maximize my use of the CPU. Seems like I can have XMP enabled with MCE disabled, but I'm not sure if there is any difference/benefit (cinebench doesn't think so). I know XMP is an overclock, but are there any particular settings (voltage or otherwise) I should boost when enabling XMP but keeping the CPU "stock"?
  
• What settings should I examine if I want to enable MCE, but pushing just to get the processor to run at the turbo boost of 4.3 GHz for a longer period (or sustained) without boosting the temp too much (ie. increasing the TDP from 65W to 80W or something along those lines).
  

Any advice is always appreciated. Thanks! I'm excited to be here and having fun so far.

[Raja]

AWDSOME wrote:

• Is this the expected behavior of the Coffee Lake CPUs? Spending some time at 4.3 GHz and then reducing?
  
• Given I have no experience Overclocking, I would like to have XMP enabled and still maximize my use of the CPU. Seems like I can have XMP enabled with MCE disabled, but I'm not sure if there is any difference/benefit (cinebench doesn't think so). I know XMP is an overclock, but are there any particular settings (voltage or otherwise) I should boost when enabling XMP but keeping the CPU "stock"?
  
• What settings should I examine if I want to enable MCE, but pushing just to get the processor to run at the turbo boost of 4.3 GHz for a longer period (or sustained) without boosting the temp too much (ie. increasing the TDP from 65W to 80W or something along those lines).
  

Any advice is always appreciated. Thanks! I'm excited to be here and having fun so far.

1. Yes, the processor speed should modulate according to load.

2. It's okay to run XMP without MCE. If the system is stable, you don't need to make adjustments. When you feel more confident, you may want to consider tweaking voltages, as you may be able to reduce the system agent and IO voltages to a value lower than what the UEFI applies.

3. The highest current rail associated with core temperatures is Vcore. You may want to see if the CPU is stable at a lower value. Some of the secondary voltage rails such as System Agent, and the IO rail, make a smaller contribution. Outside that, you could try fiddling with the long and short duration power limits, which will determine how long the CPU stays in turbo state. These are not necessarily trivial tweaking practices, though.


-Raja