Testing
One advantage of having an externally mounted radiator is you will typically get better performance. This occurs because the radiator will have better unrestricted access to cooler outside air than it would have while mounting inside a case. With the AX240 installed externally, we ran it through our normal tests to see how it fairs against the same radiator mounted internally.
The test rig consists of the following parts:
Processor: Intel Core i5 2500K
Motherboard: ASUS P8P67 EVO
Video Card: SPARKLE Calibre Series X480 GeForce GTX 480
Memory: Corsair Vengence 8 GB @ 1600mhz
Power Supply: High Power Astro PT 700w
Storage: OCZ Vertex 2 120 GB Running Windows 8 64bit
Cooling: XSPC RayStorm 750 RS240 w/ AX Radiator Desktop Stand
Case: Nanoxia Deep Silence 1
Testing was done using Intel Burn Test (IBT) with the AVX instruction set. The reason I use this instead of Prime95 with this setup is that it pushes our i5 2500K a whole lot harder, giving us a better sense of load temps. Most of the testing was done at the high memory setting for a single pass. While admittedly this in no way would qualify the chip as stable when overclocking, it gives us a realistic idea of what temps it will be hitting.
Stock Intel cooler results:
Ambient temps: 22.22C/71.99F
Idle temps: 31.25C/88.25F core average
IBT temps: 78.5C/173.3F core average
With the AX240 installed externally and using the Raystorm 750 kit with the same CPU block mount here are the results with stock settings:
Ambient temps: 22.78C/73F
Idle temps: 31.5C/88.7F core average
IBT temps: 45.75C/114.35F core average
With the AX240 installed internally and using the Raystorm 750 kit here are the results with stock settings:
Ambient temps: 20C/68F
Idle temps: 30.5C/86.9F core average
IBT temps: 43.75C/110.75F core average
At first glance it looks like the internally mounted AX240 actually performed better, however when you adjust for the higher temperatures of the external test it beats it in both categories.
Now for the real test, I applied the same 5.0ghz overclock to the 2500K that the internal AX240 had and this is how the external mount performed:
Ambient temps: 22.78C/73F
Max overclock: 5.0 ghz/1.504V vCore
IBT temps: 79.25C/174.65F core average with a high core temp of 85C
Internal Mount:
Ambient temps: 20C/68F
Max overclock: 5.0 ghz/1.504V vCore
IBT temps: 74.5C/166.1F core average
So it seems that at the higher clock the internal mount wins even when adjusted for the temperature difference. There is one thing that I believe can explain this though, and that is the pump. The 750 pump that is included with the kit is simply not very strong. With the added hose length and extra water volume I believe our flow rate has dropped to the point that it is detrimental to the cooling capability of the radiator.