Watercooling VRs – Nick Poirier
Introduction
This is my third article for Overclockers.com and it is really an extension of my second article. The second article discussed the installation of a custom water block on top of my motherboard’s CPU voltage regulators. Apparently that article has sparked a lot of interest among the readers of Overclockers.com as I have been receiving a lot of emails from people regarding it.
However, several people let me know that I should have actually tried to cool the bottom of the voltage regulators – and not the top as I had done. This is because it is really the bottom of the VRs which is their hottest side and that it is the bottom of the VRs which is supposed to be cooled. And they’re right!
Consider this example: Anyone who has seen the inside of a PC power supply has seen the large aluminum heatsinks in there. And if you look closely, you will see the heatsinks are attached not to the top side of the VRs but rather to their bottom side. Thus cooling the bottom of the VRs is the correct (and more useful) method.
So, in this third article I will discuss how I set out to cool the correct side of the VRs…by making another VR waterblock and installing on the back-side of the motherboard.
The VRs on my motherboard are surface-mount components…thus they do not have legs which go through the motherboard
With that in mind, I took a look at the back of the motherboard to see if there was a flat area in which a water block could be installed
And luckily the area in question is mostly open and accessible
There is a strip of open space which is almost 1″ wide right below where the VRs are located on the top-side
There are many obvious solder points to avoid where the legs of other components stick through the motherboard
However, there are also many small “bumps” of solder which are all around the area
These “bumps” of solder stick up off the surface a little but can barely be felt with you fingers
Nevertheless these bumps had to be considered during the planning stage
As a test to see if cooling the back of the motherboard was even worth doing, I needed to cut an access hole in the motherboard tray
The intended target: my Lian Li PC70′s motherboard tray
I cut the hole using my Dremel and those expensive fiberglass reinforced cutting discs
I didn’t want to cut away too much of the metal as that would weaken the rigidity and strength of the tray
Now to measure how hot the back of the motherboard was getting
I routed a temp probe back behind the motherboard and taped it in place right in the middle of that open area
And this is the temperature I recorded:
LEFT = coolant temp…RIGHT = back of mobo
~75′C !!!
At the time I recorded those temps, my CPU was running ~2680 MHz @ ~2.0v and running Prime95 for about 5 minutes
The idle temp for the back of the motherboard was about 60-62′C
But remember…I already have a block installed on the top of the VRs
And at the time I recorded those temps, I was running my PC with the side panels OFF
Not to mention that the hole which I cut in the mobo tray was probably allowing some of the heat to radiate out more easily
So at this point I was convinced cooling the back of the motherboard would help
{mospagebreak}
Nick Poirier
To make the back-side block, I used a somewhat similar method which I used to make my top-side block
For this one I used some copper flat-bar, 25mm wide and 3mm thick (approx. 1″ and 1/8″)
Some thin copper sheet, 1mm thick (approx. 1/16″)
And some copper pipe, 10mm OD and 8mm ID (approx. 3/8″ OD, 1/4″ ID)
The flat-bar will be used for the base, the thin sheet will be bent to form the water chamber and the pipe will be used for the inlet/outlet connectors
Next I drew up some quick plans to make the water chamber
I would end up changing these plans slightly to make the block fit and to make it easier to build
Here is the piece of the copper sheet I cut to make the water chamber
I used a hacksaw and it was really easy to cut
Next I marked out the cut and fold lines
Here is the copper sheet cut to size with the inlet/outlet holes drilled
I used my Dremel and those fiberglass reinforced cutting discs to make the cuts this time
Again the metal cut very, very easily
Here is the base of the block cut to length (75mm)
I had to make some notches in the side and trim the lower right corner to avoid contact with some solder points on the underside of the motherboard
It was these notches which forced me to adjust my original dimensions for the water chamber (the water chamber had to be reduced from 15mm to 12mm wide)
I also planned on bending out the bottom 2mm of the edges of the water chamber so that it would have a flat surface to meet the base of the block
However, I found it next to impossible for me to bend the thin copper sheet in this way by hand
I would have needed a nice bending machine to get the 2mm lip I wanted at the bottom
Here you can see the inside of the water chamber after folding up the thin sheet copper
Folding the copper was somewhat difficult – time consuming mostly
I used my hands and some regular pliers to do the bending
The inlet/outlet pipes were cut to no particular length
The ends of the pipes which get attached to the block were cut at an angle to correspond to the shape of the block
Also, I drilled lots of “divots” or “starter” holes in the base where the water will flow
The block is basically open on the inside with little flow restriction, but it was my hope that the holes will help increase the surface area in contact with the coolant and to maybe disrupt the flow a little
Nick Poirier
Here is the block ready to be soldered
And here is the block all soldered
I tested the block for leaks and there were none
I spent a little time cleaning up the block
I tried to file away most of the excess solder but I really didn’t put a great deal of effort into it since I will never see the block
I used some 400 grit sandpaper and some metal polish/cleaner to finish up
The block is now ready for installation
This is where the block is going
My plan is to use thermal tape to act as the separating layer between the copper block and electrical traces on the motherboard
I didn’t plan on the using thermal tape alone to secure the block
So I had to design some kind of mechanism to hold the block in place
I made a hold-down bracket out of some aluminum square tubing I had lying around
Due to the tight space limits behind the motherboard, I had to cut the aluminum tube in half lengthwise and file down the edges a little
I also had to worry about the heads of the mounting screws possibly touching some solder points on the back of the motherboard
The original hole I made in the motherboard tray had to be increased somewhat to allow for the hoses to get connected more easily
And here is something I had not considered at all during the planning/construction of the block
The side panel of my Lian Li PC70 has a handle which is “punched” into the metal surface
This area, of course, is right where the block is getting installed
This handle reduces the depth of the overall space I have to work with between the back of the mobo and the inside surface of the installed side panel
Thankfully, just by pure luck, the handle ends up right between the two mounting screws (where there is some free space)
I remember saying some choice words when I realized I forgot about the handle on the side panel 
Nick Poirier
The hold-down bracket I made works great
It can apply plenty of down-force on the block and it doesn’t flex the motherboard tray out of shape (even in its cut-up state)
I didn’t tighten the nuts too much…just as much as I could with my fingers
I was worried about those small solder “bumps” I mentioned before working their way through the thermal tape if I put too much pressure on the block
Here are some pictures of the block installed with the bracket holding it in place:
This picture is from the side and shows the tight space constraints behind the motherboard
My camera was half inside the case looking down the length of the case
At this point, I knew that the block fit onto the motherboard and it was ready to be fully installed
So that meant I needed to apply the thermal tape to the base
The thermal tape I used came from some Thermaltake heatsinks I came across during my job as a PC repair tech
Nick Poirier
Here the block is installed on the motherboard with the thermal tape in place
The thermal tape actually holds the block in place VERY well – I am quite surprised!
After seeing how well that thermal tape worked I am not worried in the slightest that the block will shift, slide over, and make contact with any of the surrounding solder points sticking up around it
Here the hoses are hooked up to the block
I used plain regular nylon hose
The top of the block is where the coolant comes in and the bottom is where it exits
In this particular circuit, the coolant comes up from the pump, goes thru the top-side block, loops back and down thru the new back-side block, then returns back to the reservoir (ie no rad in this loop)
And how well does it work, you ask?
Here is a temp readout with the back-block installed (again…LEFT = coolant temp, RIGHT = back of mobo)
That picture was taken with my CPU running @ ~2600 MHz, 1.95v, 100% load running Prime95
Remember that the motherboard temp before my new back-side block was ~75′C during 100% load times!!
{mospagebreak}
Nick Poirier
Some Results
The biggest change I have noticed since the addition of the back-side block is that my available CPU voltage has been increased and that the CPU voltage has stabilized
My NF7-S Rev.2 motherboard allows you to select a CPU voltage as high as 2.3v but anything over 2.125v would make the system hang during POST
I was never able to use a voltage above 2.125v (no matter what my CPU speed, multiplier, or FSB was)
Now with the increased cooling, I can use a CPU voltage as high as 2.22v (2.25v or higher still locks up the system)
Also, the CPU voltage does not vary as much anymore
Before you could see the CPU voltage changing by as much as 0.03v regularly by watching MBM
Now the CPU voltage only changes by 0.01v occasionally
Unfortunately this has not helped my CPU overclock any further really (maybe another 50 MHz)
I think I have simply maxxed out my 1700+ at ~2700 MHz with a voltage of ~2.0v
Or my 431w Enermax P/S has hit it’s limit
Or my cooling system has hit its limit for cooling a CPU at this MHz/voltage
The higher CPU voltage would be useful if I was super-cooling the CPU I assume
I am just running plain water-cooling here…pump, blocks, rads
Interestingly, my reported CPU temperature did not get affected by reducing the excess heat around the CPU socket
I thought for sure I would see the CPU temp drop a few degrees, but it hasn’t happened
MBM still reports the same CPU temps I am used to seeing
However, if the reported CPU temp dropped, say 10′C, I realize that my CPU would probably still be running as hot as it always was
I was hoping for a few ‘C temp drop though
Maybe the latest BIOS for the NF7 reports the internal CPU diode temp instead of the in-socket probe temp??
My FSB still maxes out at ~223 MHz, but I think that’s because I am just running the chipset at 1.7v (the max in the BIOS)
Conclusions
Making the back-side block was a fun experience – I am glad that I did it!
With my particular water-cooling setup, it was not hard to add another block to the system
However, it was a lot of work to plan, build and install the block
I still felt it was certainly something worth trying!
And there’s always the bragging rights
However, I am sure that I have not fully discovered all the potential pro’s and con’s of using a back-side block
There may be problems or issues that have yet to surface from this
So at this time I cannot recommend that everyone try this in their systems
Installing a copper block on the surface of the motherboard might not work for everyone
The obvious benefits which I have discovered so far is that the max available CPU voltage went up and that the CPU voltage did stabilize a lot
If your system suffers from a low and/or erratic CPU voltage, then maybe this is something worth looking into
Also the excess heat around the CPU has been significantly reduced
And the cost of the materials to make the block was very low (maybe $5 MAX) which is always good
Thanks for reading!
- Watercooling Motherboard Voltage Regulators
- Boosting Motherboard 5v by Adding Regulators
- A New Approach To Water Cooling
- How To Add A Blowhole To Your PC – And A little Extra Backside Video Card Cooling Too
- System Cooling: A Dual Pronged Approach
Tags: Motherboards
