I've run an overclocked i7 4930K for some years, not for gaming but fast rendering and editing of large HD video movie files. I use a Laing D5 vario pump, copper water blocks on the cpu,gpu and memory cards, with a triple fan radiator. I have a 51/4" perspex drive bay reservoir in the loop with tell tale turbine flow indicator (highly recommended).
I first started to notice I was always topping up the coolant frequently, despite air pressure testing the loop for leaks. This really puzzled me and I wondered if the clear 1/2" silicone hose I was using could somehow leech water? Then I noticed a build up of algae in the perspex reservoir, even though I was using a biocide and a silver coil.
Then I thought the flow rate was low, so I increased the pump speed. CPU core temps were still good running Prime95. Then last week I started getting BSODs at boot and had to reduce the OC from 4.4Ghz to 4.2 Ghz to get a stable OC. Even when new, my cpu has never done better than a marginal 4.5Ghz.
I started looking at my cooling system. To my surprise I discovered the triple radiator was aluminum and despite using good coolant mixture had corroded and no coolant was flowing through it! It was so corroded I had to saw off the terminals to remove my elbow connectors. This explained why I was always topping up the loop because whilst blocked, water couldn't flow through but air could be trapped inside and was slowly leaking back into the loop after I thought it was full!.
This made me think that mixing copper and aluminum metals in a closed loop might not be a good idea and when looking at radiators it was important to balance higher efficiency narrow core tube against lower efficiency wider cores less likely to block? When you look at radiators they often spec. the fins per inch (FPI), but rarely the internal size of the core tubes although a clue here would be a pressure drop or flow rate reduction figure if measured. Because of this trade off of core tube diameter and core density, a deeper radiator is more likely to have less flow resistance and wider core tubes than a thin slimline radiator offering a similar thermal efficiency? Increasing the FPI increases radiator efficiency, but you need the fans working harder and noisier to pull air through. My i7 4930K still runs OC'd at below 130 watts and core temps just below 70C on Prime95. A litre of coolant and triple fan radiator has always been o.k even in Summer.
I replaced the blocked and corroded ali radiator with a Magicool Copper Radiator III-360mm from Overclockers which was a fairly easy swap. This might not be a high end radiator, but it does have 2mm core tubes. My flow tell tale rotates much faster, I can reduce the D5 vario pump speed to a slower quieter settings and everything is staying cool.
The only problem I'm left with is something has changed in the CPU as I can't hit 4.5Ghz anymore (although 4.2 is still o.k) The BSOD message refers to a clock not arriving in time on one of the 6 cores? Since this cpu has never given more than 4.5Ghz OC, I think it has just lost a little headroom caused by my cooling problems.
I first started to notice I was always topping up the coolant frequently, despite air pressure testing the loop for leaks. This really puzzled me and I wondered if the clear 1/2" silicone hose I was using could somehow leech water? Then I noticed a build up of algae in the perspex reservoir, even though I was using a biocide and a silver coil.
Then I thought the flow rate was low, so I increased the pump speed. CPU core temps were still good running Prime95. Then last week I started getting BSODs at boot and had to reduce the OC from 4.4Ghz to 4.2 Ghz to get a stable OC. Even when new, my cpu has never done better than a marginal 4.5Ghz.
I started looking at my cooling system. To my surprise I discovered the triple radiator was aluminum and despite using good coolant mixture had corroded and no coolant was flowing through it! It was so corroded I had to saw off the terminals to remove my elbow connectors. This explained why I was always topping up the loop because whilst blocked, water couldn't flow through but air could be trapped inside and was slowly leaking back into the loop after I thought it was full!.
This made me think that mixing copper and aluminum metals in a closed loop might not be a good idea and when looking at radiators it was important to balance higher efficiency narrow core tube against lower efficiency wider cores less likely to block? When you look at radiators they often spec. the fins per inch (FPI), but rarely the internal size of the core tubes although a clue here would be a pressure drop or flow rate reduction figure if measured. Because of this trade off of core tube diameter and core density, a deeper radiator is more likely to have less flow resistance and wider core tubes than a thin slimline radiator offering a similar thermal efficiency? Increasing the FPI increases radiator efficiency, but you need the fans working harder and noisier to pull air through. My i7 4930K still runs OC'd at below 130 watts and core temps just below 70C on Prime95. A litre of coolant and triple fan radiator has always been o.k even in Summer.
I replaced the blocked and corroded ali radiator with a Magicool Copper Radiator III-360mm from Overclockers which was a fairly easy swap. This might not be a high end radiator, but it does have 2mm core tubes. My flow tell tale rotates much faster, I can reduce the D5 vario pump speed to a slower quieter settings and everything is staying cool.
The only problem I'm left with is something has changed in the CPU as I can't hit 4.5Ghz anymore (although 4.2 is still o.k) The BSOD message refers to a clock not arriving in time on one of the 6 cores? Since this cpu has never given more than 4.5Ghz OC, I think it has just lost a little headroom caused by my cooling problems.
