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Question Intel Coffee Lake (9700K) Question - How to Limit Power Usage?

blckgrffn

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May 1, 2003
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Hey all, I need some guidance.

I've been watching Microcenter for a bit now for Zen 2 deals as Zen 3 approaches.

But... right now they have i7 9700k's for $220 with $40 off a motherboard.

Also right now, both of my kids have Intel 3xx chipset computers and an i3 and an i5 respectively. We use these for gaming, mostly SC2 right now but as the years go on we'll likely progress into more involved games. Older boy has a RX 470, girl has a GTX 970 and these seem "fine" for the moment.

I could get some cheap motherboards bundled with these CPUS and sell them as "brand new" with the accompanying CPUs, or even find a reason to retire a 920 AM2+ Phenom 2 that my daughter uses every day for remote learning in our living room. Also, I think theses CPUs will likely hold value well given the are upper range Intel chips and that seems to be the case. They may not be under $150 for years and years from now. So I could be looking at ~$100 per PC to get them to i7 K cpus.

That seems like a lot "drop in" CPU for the money. It also seems like this window opens and closes quickly at the end of a socket with Intel and Microcenter in particular.

The thing is, one of the kids has a Hyper 212 with a upgraded fan, the other a 95W rated Arctic Cooler. I don't really want to invest in better coolers as well, because then that seems like the hassle factor is getting a little high.

So here is the real question.

Can I limit Intel 9xxx series CPUs to a max power (100W)? Via UEFI, ideally? And if so, how big of detriment to performance is it?

If all core can still be 3.6 ghz and I can dual core boost to ~4 ghz or so and keep it to ~100W I think both the power delivery systems and the cooling systems of the boards could take it.

I would always know that I am a 240mm AIO (which their cases could easily support) or ~$50 air cooler away from getting full clocks. I wouldn't intend to ever turn them up much if at all past normal K clocks.

Or am I just making a mistake spending money on dead end tech?
 

coercitiv

Diamond Member
Jan 24, 2014
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Can I limit Intel 9xxx series CPUs to a max power (100W)? Via UEFI, ideally? And if so, how big of detriment to performance is it?

If all core can still be 3.6 ghz and I can dual core boost to ~4 ghz or so and keep it to ~100W I think both the power delivery systems and the cooling systems of the boards could take it.

I would always know that I am a 240mm AIO (which their cases could easily support) or ~$50 air cooler away from getting full clocks. I wouldn't intend to ever turn them up much if at all past normal K clocks.

Or am I just making a mistake spending money on dead end tech?
Price looks very good and you can definitely keep thermals under control while keeping most of the performance. In gaming you should get 100% stock performance even with the Hyper 212.

All you need to do is check your current motherboards for power limit settings. They tend to have different names depending on manufacturer. On my MSI board they're called "Long Duration Power Limit" and "Short Duration Power Limit". One controls long term power draw (PL1) and the other is for short term (PL2), hence there will also be another parameter for setting a time limit. You can set PL1 to something like 90-100W and can also optionally configure PL2 at 100-110W for 20-30 seconds.

For starters you can test the feature with the current CPUs installed, long term power draw can be set as low as 25-35W and still work as intended.

As a reference point my i7 8700 goes to 120W @ 4.3Ghz under AVX loads but around 95W in Cinebench, while gaming power consumption is way lower. With 100W power limit on the 9700K I would expect something like 3.9Ghz+ in AVX and 4.4Ghz+ in Cinebench. Gaming loads should reach 4.6Ghz stock all-core boost.
 
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blckgrffn

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@coercitiv thanks man! I’ve got a nice MSI board and a cheaper Gigabyte board and I’ll check it out.

Since these are mainly gaming and “general” use and gaming PCs and not Blender or Distributed Computing focused I am stoked to hear they might keep a lot of performance even with more modest power levels.

👍😎
 

blckgrffn

Diamond Member
May 1, 2003
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Well, they had 10+ of the CPUs yesterday and 7 today. I just placed an order for one to go with my daughters Z370 board and picked up a decent but $55 after $40 (!) off discount Asrock B365 ATX sized board. Less than $300 out the door for CPU and board w/tax.

1603582889089.jpeg

Pretty sure this is the configuration I needed. Discovered it’s a nicer B360 board actually and not the Z board I thought it was but it should still be fine so long as I can throttle it down. I may set a pretty aggressive AVX offset too just to ensure nothing gets out of hand.
 
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blckgrffn

Diamond Member
May 1, 2003
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www.teamjuchems.com
B11182F0-01A5-41B0-8876-8528F4560AE7.jpeg

Well, I hauled in this:

9700k ($220)
9700f ($190)
Asrock B365 ATX board ($56 after $40 board discount from 9700k)
2x 16GB kits of Geil 3000 CL16 ram ($62 total)

Total: 567 after tax

I would have done the 9700k deal twice as I think that it’s just a more versatile CPU and easily worth $30 extra bucks even without a board discount but they sold out this morning. I am pretty sure that’s the end. Going to keep it all boxed up as I’d rather get a sick deal on AMD parts after Zen 3 drops but I don’t think the deals will be as good as in the past as the steam is really on the AMD parts now. We will see.

I will report back on performance with lower power usage limits in place if/when they get installed :)
 

coercitiv

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Jan 24, 2014
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The one thing I'll be curious about is whether you can overclock the memory or not. (oc as in use it with XMP rated clocks)
 
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blckgrffn

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May 1, 2003
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www.teamjuchems.com
The one thing I'll be curious about is whether you can overclock the memory or not. (oc as in use it with XMP rated clocks)
Me too. At $31 per kit, I had to bring it home.

Which is pretty much the story of this whole endeavor. Otherwise it's too fast for Intel and too slow for a Zen 2 or likely Zen 3? lol. I'd read some people got really good memory that OC'd well in these kits so we'll see.
 

blckgrffn

Diamond Member
May 1, 2003
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www.teamjuchems.com
Update:

Installed the first 9700k into my daughters PC that had a MSI B360 Gaming motherboard (notably, the power delivery system around the CPU has heatsinks) and it went fine.

Power limits set to 100W long turbo, 110W short turbo and still seeing single thread boosts way into the upper 4ghz range and during the all core stress test in the Intel Overclocking Utility it got down to 3.8 to 4.0 ghz during the most strenuous tests and was flagging that it was power level limited - just as intended.

Also, I was able to enable the XMP profile on the $30 16GB kit 3000mhz memory, the board was smart enough to take the timings and voltage and then set it to the max supported chipset frequency of 2666. Keeping it easy.

Oh, and after the weekend Microcenter shifted the deal from $220 processor/$40 off motherboard to $200 processor/$20 off motherboard for whatever reason, so I chatted them up and got a $20 refund on that CPU and the 9900K that I went back down to get for a friend. I returned the 9700f outright because it just didn't feel like a good value @ $190 when I could get 9700ks for $10 more.

Woohoo ;) This feels a lot like when I built out a few systems with FX 8310's or whatever back in the day. 8 cores, too much power, passible performance :p

OK, way better performance comparatively to that time. For at least the next day.
 
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