Corsair recently released two new custom liquid cooling kits – the Corsair Hydro X Series Starter Kits; Corsair XH305i RGB and XH303i RGB. These kits are aimed towards (beginner) water cooling enthusiasts who want to build a custom water-cooling setup for their PC. The Hydro X Series already includes all the things that you need to build a great looking hardline custom loop, including the bending kit. So, what’s the difference between the Corsair XH305i and XH303i? And which one should you get? Let’s compare them below.
Corsair Hydro X Series HX305i vs XH303i Custom Hardline Water-Cooling Loop Starter Kits
Building a system with a hardline custom water-cooling loop keeps getting better and easier thanks to starter kits like Corsair’s Hydro X Series. These starter kit come with all the things that you need to build a great looking custom water-cooled (gaming) rig.
Out of the box, the starter kits include an RGB CPU water block; a 360mm radiator; three RGB fans; PMMA clear hardline tubing; a hardline cutting/bending kit; fittings and adapter; and coolant. The thermal paste is pre-applied on the CPU water block.
While everything seems to be included in the package, you do still a heat gun to soften and bend the tubes. You’ll also need some distilled water to clean and flush the debris that is left inside the tubes and perhaps the radiator as well.
What’s the Difference Between XH305i and XH303i?
There are three main differences between the Corsair HX305i and HX303i RGB starter kits. First is that the HX305i comes with a Xylem D5 PWM pump or XD5 RGB pump/reservoir combo. Meanwhile, the XH303i is bundled with a Xylem DDC 3.2 PWM9 pump or XD3 RGB pump/reservoir combo.
Corsair Xylem DDC 3.2 PWM9 pump with reservoir combo 
Corsair Xylem D5 PWM pump with reservoir combo
D5 Pump vs DDC Pump?
These two are the most common type of pumps used on a custom water-cooling loop. In a gist, D5 pumps are usually larger compared to DDC pumps and typically offer a greater flow rate at a lower pressure than a DDC pump. Meanwhile, DDC pumps are usually smaller; offers a lower flow rate but higher pressure compared to D5 pumps.
DDC pumps tend to be more audible compared to D5 pumps and has a tendency to run hot. Both the D5 and DDC pumps are water lubricated. So do not turn on the pump or the loop without any liquid on it.
Finally, generally speaking, DDC pumps are great for small form factor builds with limited space. Meanwhile, D5 pumps are usually used on high-performance PCs; they are more silent and tends to be the more reliable pumps between the two.
Aside from the pump, the XH305i comes with a 330ml reservoir, while the XH303i has a 180ml reservoir. The fans are also different, with the XH305i bundled with three iCUE QL120 RGB fans. While the XH303i comes with three iCUE SP120 RGB Pro fans. Between the SP120 and QL120, the QL120 is the newer fan series and is built with 34 individually addressable RGB LEDs per fan.
You can check out our Corsair iCUE QL120 RGB PWM Fan review here.
These starter kits also come with Corsair’s XC7 RGB CPU Water Block. It’s compatible with Intel 1200 and 115X processors and AMD AM4 processors. A high surface area XR5 360mm radiator efficiently dissipates heat from the CPU, transferred by the included XL5 clear coolant around the loop. The included XT Hardline cutting/bending kit contains a saw, bending mandrel, tube holder, and silicone insert, making it easy to create professional-looking loops with the addition of a heat source (not included).
Finally, both kits include a Corsair iCUE Commander PRO Smart RGB Lighting and Fan Speed Controller, enabling intelligent control over your cooling through Corsair iCUE software. Use iCUE to adjust fan and pump settings, set automated fan curves, monitor real-time temperatures, customize RGB lighting, and synchronize it with all iCUE-compatible products in your setup.
I mentioned earlier that there are three main differences. So far, I only mentioned two, the pump type and the fans included. The third main difference is price.
Corsair HX305i RGB starter kit 
HX303i RGB starter kit
Corsair Hydro X Series Pricing and Availability
The Corsair Hydro X XH305i RGB kit has a manufacturer’s suggested retail price of $549.99 excluding tax; or €579.90 inc. tax, and £519.99 inc. VAT. Meanwhile, the XH303i has an MSRP of $479.99 excluding tax; or €499.90 inc. tax, and £449.99 inc. VAT.
The XH305i RGB and XH303i RGB kits are backed by a two-year warranty, alongside the Corsair worldwide customer service and technical support network. For the latest pricing and availability, you can visit the links below.
Corsair Hydro X XH305i RGB Kit available on Amazon.com here
Corsair Hydro X XH303i RGB Kit available on Amazon.com here
