Originally Posted by opt33
At 1.5 gpm, It takes 400 watts to heat water by 1C. So, in serial, the second loaded GPU may see water temps 1C higher at most. Temp differences higher than that are usually from other things like different loads between gpus, tim/contact differences, etc.
In a combined cpu and full cover 2 gpu's loop that is serial, the gpu block will get more flow (since not halved by parallel), but cpu will get less flow since suffers pressure drop of 2 gpus.
In same loop except the 2 gpus are in parallel, each gpu will get less flow, but cpu in that loop gets more flow, since gpu restriction is cut in half .
so, going serial i might get worth temp in the cpu since it will get less flow?
EDIT: found some useful information in xtremesystem watercooling guide
"So, while the overall increase in CPU temperature remained nominal (about 2%) it is also interesting to note that the parallel setup shows a measurable advantage of 0.58°C over serial as calculated in (*) below, which can be 100% attributed to a substantially lower pressure drop at the system level. And this fact clearly answers the second part of our question #2: “what GPU block configuration works best, serial or parallel?” : Clearly, the higher flow rate in the CPU waterblock and in the radiator yield a better thermal resistance and result in lower temps in a parallel setup than in a serial setup.
Finally, note 3 is of particular interest within the framework of this study, because it shows that even at the GPU level, a parallel setup with modern blocks such as those presented here remains a superior solution to serial, as evidenced by a 0.6°C advantage of parallel over serial."Edited by eduardmc - 11/27/11 at 6:11am