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 Post subject: Overclocking an i-7700k with H240X2 Prestige
 Post Posted: June 27th, 2017, 7:54 pm 
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Joined: May 12th, 2017, 7:14 pm
Posts: 21
Hi guys,

Would like some advise on the temperatures I'm seeing on an overclock of the i7-7700k using Swiftech's H240 X2 Prestige AIO.

My setup as follows:
Motherboard: Asus MAXIMUS IX FORMULA
CPU: i7-7700k
CPU cooler: Swiftech's H240 X2 Prestige AIO. Mounted at the top of the case with air path from inside the case to external environment. I.e. exhaust.
RAM: Corsair Vengeance 16GB (2x8GB) DDR4 3200
SSD: MyDigitalSSD BPX 480GB
Case: Corsair Carbide Air 540

I'm using Realbench as the stress testing software and run it for an hour to check for stability. CPU-Z to check CPU frequency and Vcore. HWMonitor for temperature monitoring.

At stock settings (i.e. no overclock and no XMP profile on the RAM), when running Realbench for about an hour, the highest core temperature is 76 deg C as shown in the picture below.
Image
Noticed the pump speed is running about 50% and there was little noise - apart from the rushing of air out of the radiator. Quite happy with the performance of the H240 X2. Under stock settings, the CPU power drawn is well below it's thermal rating.

I then set for a mild overclock. The multiplier setting was set to 48x and the CPU Core Voltage Override set to 1.35V. I then completed another Realbench run with the following results.
Image
As can be seen, one of the cores has reached a toasty 91 deg C. :shock:

The pump RPM is tied to the CPU fan header on the motherboard and during the stress test, it's close to maximum output. Under stress testing, the fans on the H240 X2 make alot of noise, mainly from the passage of air out of the radiator. When the PC is idle, the CPU core temperatures are pretty good at less than 10 deg above the room temperature. So the H240 X2 is doing it's job. Under the overclock stress test, the power drawn by the CPU is just above the 91W rating limit.

Want to know if there's an issue with the CPU? Looks like it can't go much above 4.8GHz. :( Maybe a delid and relid is the next step?


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 Post subject: Re: Overclocking an i-7700k with H240X2 Prestige
 Post Posted: July 21st, 2017, 8:45 pm 
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Joined: May 12th, 2017, 7:14 pm
Posts: 21
Did some experimentation with pump / fan speed setup to stabilize the system.

I've now connected the pump speed based on CPU fan header with 54% speed all the way up to 50 deg C. The pump speed then gradually ramps up to 80% between 50 deg C to 70 deg C, then jumps up to 100% as the temperature climbs up to 75 deg C and beyond. Hysteresis control has been implemented such that sudden changes in CPU temps will cause the pumps to gradually increase or decrease in speed.

The radiator fans of the H240X2 are connected to a separate fan header on the motherboard. The fans operate at a minimum of 30% speed up to 50 deg C then gradually ramp up to 50% speed when CPU temp climbs up to 70 deg C, then a jump up to 100% at 75 deg C and beyond. Hysteresis control has been implemented such that sudden changes in CPU temps will cause the radiator fans to gradually increase or decrease in speed.

Discovered der8auer's settings for overclocking Kabylake processors on ASUS motherboards at lower Vcore=1.300V and 49x multiplier gave good stability results on Realbench as shown in the below screen shot after 90 minutes. Test was completed after 120 minutes.
Image
With the silicon lottery in full swing, looks like I got a potato chip. :cry:
At 4.9MHz, the maximum CPU package power is a little over 97W. Maximum core temp is 83 deg C. These results are okay for 24/7 operation and long term stability.
Have ordered a delid/relid device to see if the Vcore temp can be lowered further and obtain some additional thermal headroom.

Overall the system operates in a quiet mode and the main noise is from the case fans and HDDs. Will be replacing the case fans with better and more silent fans, but scratching the head on what to do with those noisy 3.5" HDDs? :?:

The intent is reach the magical 5.0GHz. Below is a screen shot of the system running Realbench after 2 hours with Vcore=1.380V, resulting in significant increase in thermals.
Image
Note that Core Max temps climbed up to 91 Deg C! :shock:

Thinking about implementing a delta T between case air temp and water temp to control the fans on the radiator. Aquacomputer offers the aquaero 6 LT USB fan controller which is an interesting option. Would like to know if anyone has successfully implemented an aquaero with their Switftech gear? If so, is there any gotchas that one should look out for?


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