This thread is also going to serve as my ongoing worklog as I overclock. Results summary will be appended to the bottom of this post.
The system is built and happily chugging away at FAH and burning that chip in. It is time to start designing the water-cooling.
CPU: Core i5 750 Purpose:
RAM: G.Skill 7-8-7-24 DDR3-1600 Ripjaws
Motherboard: Asus P7P55D-E
Video: XFX Radeon HD 5770
PSU: OCZ z-series 550w 80+ silver cert.
Overclocking: The system will run over 4GHz ... aiming for at least 4.5 (215 x 21)
Quiet: The system must be whisper quiet. I don't want to know when it is on.
Initially, I will be cooling only the CPU. The loop will be expanded to cool the GPU and chipset. This is the main reason that I'm building a complete system rather than simply using a ready-made solution such as Corsair's H50.Preliminary DesignSet-Up
The pump and reservoir will go under the HDD in the space that the CM 690 provides for all those extra drives. I only plan to use two HDDs and I can always put one or both up in the external slots if necessary. The reservoir is a cylinder design that can be mounted on any of the pillars in the case, making it easy to add a second if necessary.
The first rad will go on the top of the case. Initially, the loop will be:
Pump -> temp gauge -> CPU waterblock -> Radiator -> Reservoir -> Pump
Notice that the temp gauge comes into the loop just before the CPU waterblock. Since the CPU is the part being cooled, I want to ensure that the water is cool before it hits the waterblock. Cooling the CPU with hot water is a definite no-no.
Adding the GPU block, chipset and MOSFET blocks and a second radiator will come later. I intend to put the second radiator at the front of the case (where there is already a fan) and run the loop as follows:
Pump -> temperature gauge -> CPU waterblock -> MOSFETS -> Rear Radiator -> GPU -> Chipset -> Front Radiator -> Resevoir -> Pump
You can see why I think I need a powerful pump for this loop.
Again, the temp gauge comes into the loop right after the pump. My reasoning is a bit different this time. The water should be (must be) coolest as it leaves the reservoir and begins the cooling cycle. Thus, I want to be able to see the water at its coolest to ensure that it is capable of absorbing and releasing the thermal load placed on the watercooling loop by the system.
An alternative that occurs to me is to split the loop into two. One loop would cool the CPU and MOSFETs and the other would cool the GPU and chipset. Each loop would share the pump but have its own radiator.
At this point, I'm looking for comments and criticism on all points. The parts chosen and the loop(s) proposed. The point that has me most concerned is actually the pairing of components in the second half of the project. Would I be better to pair the CPU and chipset and the GPU and MOSFETs, say?
Overclocks will start with the 'stock' overclocking settings provided by ASUS' BIOS. Stages One, Two and Three are at 2.8GHz, 2.93 GHz and 3.2 GHz respectively. I'll post up the full details if anyone is interested, but for now I'll just list the BCLK and multiplier settings.
All chip features will be enabled unless otherwise mentioned. This means that Turbo and Speedstep will be left ON until I find it necessary to disable them for higher clocks.
Finally, I won't be benchmarking the system. The idea is to determine the thermal load that each cooling system is capable of handling. I will be benchmarking the system when I'm done in order to find the best overclocking settings for my application but that will appear in a different worklog. For this particular task, I will be pushing the CPU as far as I can with each cooling system. Once I've determined the thermal limits of my system, then I will go back and tune the CPU / BCLK / RAM relationships to push the most bits.
Note that initially, I will only be overclocking the CPU. In time, I will also be overclocking the GPU as well. I will measure the effectiveness of the stock GPU cooler before replacing it with a waterblock in the third portion of this project.Stock cooler temps at full load (FAH pushing all cores to 100%)
No voltage increases attempted with stock cooling.Stock settings: 2.67GHz
CPU: 61CStage One Overclock: 2.8 GHz
CPU: 58CStage Two Overclock: 2.93 GHz
CPU: 61CStage Three Overclock: 3.2GHz
CPU: over 75C ... PC manually shut down after 2 minutes of FAHMaximum Overclock with Stock Cooler: (so far) 3.15GHz
Note: The third stage is just too much for the stock cooler. Temps rose above my maximum allowed of 75C within minutes of starting Folding@Home
CPU: 70CCorsair H50 at full load with folding@home pushing all four cores to 100%
The H50 has two fans mounted on the radiator. The fan that was included with the kit and a Scythe S-Flex SFF21F are both pulling air from outside the case, over the rad and into the case.
I also have a 120mm fan mounted on the side panel pushing air out and another 120mm fan mounted in the front pulling air in over the single HDD.
The first set of test will duplicate the same settings used with the stock cooler to compare temps.
All settings stock:Stock settings: 2.67GHz
Interesting to note that the CPU temp dropped 20C but the MB rose by 5C. Perhaps because the fans are pulling air over the radiator and into the case?Stage One Overclock: 2.8 GHz
Absolutely no increase from stock.Stage Two Overclock: 2.93 GHz
An increase of 1C over stockStage Three Overclock: 3.2GHz
CPU: 47CStage Four Overclock: 3.6GHz
At this speed, the stock fan was inadequate to cool the CPU. With the H50, the CPU is cooler than the stock fan at stock speeds.
CPU: 49CStage Five Overclock (part one): 4.0GHz
CPU Voltage: 1.2V
Voltage increased by .05v to 1.2V
CPU Diff Amp: 900 mV
CPU Voltage: 1.4V
Integrated Memory Controller Voltage: 1.38125V
With these settings, the PC was rock stable but ran very hot .. at the limit of my threshold for safety. Asus claims that the board will not run stably at or above 200BCLK with less than 1.4V on the CPU and my tests confirm this with my board. I decided to tweak the settings to see what I could do to get 4.0GHz with less heat.Stage Five Overclock (part two): 4.0GHz
CPU Diff Amp: 1000 mV
CPU Voltage: 1.325V
Integrated Memory Controller Voltage: 1.325V
Temps dropped 10C with the new settings. This is the best I could do at 4GHz. Obviously, I'm approaching the limit of what this cooler can accomplish on this CPU .. but a 50% OC is an excellent result for a boxed cooling solution.
As with the stock cooler, the next step will be to see how far I can go while keeping the temps below 75C and the PC completely stable.Maximum Overclock with H50: 4.2GHz
CPU Diff Amp: 1000 mV
CPU Voltage: 1.375V
Integrated Memory Controller Voltage: 1.325V