Restriction (Pressure Drop) Testing
In a CPU only block type loop, restriction has little meaning as long as you can bleed out your loop. High or low restriction doesn’t necessarily relate to good or bad performance. Surprisingly you will see blocks with lower restriction also at times perform better than blocks of higher restriction. A lower restriction block simply means you’ll retain higher flow rates for other parts in your loop and may require less pumping power or be more compatible with more complex loops. In a multiple block loop, that means your GPU blocks and radiators will net slightly better performance because of the increased overall system flow rate, but that gain is always fairly small (couple of degrees). Blocks with really high restriction may also need a stronger or multiple pumps with multiple blocks loops sooner than blocks with lower restriction. It’s a balancing act of sorts, ultimately we would like to see high thermal performance at all flow rates and very low restriction…yet practically there is some give and take between the two.
I would simply suggest the following:
- CPU only loops with a strong pump – Ignore restriction, and base your performance purchasing decision on thermal performance only.
- Multiple block loops with a strong pump – Consider restriction. Average to low restriction blocks will help maintain reasonably good flow rates.
- Multiple block loops with a small pump – Strongly consider restriction. Low to very low restriction blocks may be required to maintain reasonable flow rates.
Continuing the same test method as before, I’m measuring restriction or pressure drop over the range of possible flow rates to get a complete look.
The Raystorm samples tested low in restriction. Not quite a low in restriction as the DT 5Noz, but still very good and low.