When it comes to extreme cooling that is viable for long-term use, we would be hard-pressed to name a technology that is more exciting or capable than phase-change cooling. That is why we were excited when an OCZ representative gave Icrontic the opportunity to have a hands-on look at a release sample of an OCZ Cryo-Z unit, first announced all the way back in January of 2006. It is important to note that this is not a review or a comprehensive analysis, as we only had a few hours to look at the unit in operation, but we were happy with what we saw.
Principally, phase-change cooling is a relatively simple procedure. A gaseous refrigerant is piped through a compressor, not unlike those found in freezers or refrigerators, and cooled to a liquid state. The compressed liquid is then pumped to a copper plate known as the evap head which makes contact with the processor itself. The aptly-named evap head is responsible for changing the phase of the refrigerant back into a gas, thereby sapping heat from the CPU. The gas then returns to the refrigerant tank where the process begins anew.
The unit comes in stylish brushed aluminum with several machined vents backed by black mesh and weighs in at a meaty 26 kilos/50.6 pounds. The performance of the unit was admirable, and we’ll touch on that before we come back to the few issues we had with build quality.
The test setup
- Intel Core 2 Quad QX6850
- ABIT IX38 QuadGT
- 2x1GB OCZ Reaper HPC PC2-9200
- AMD Radeon 3870s in Crossfire
While the QuadGT employs digital PWM, it is only a five-phase design. With more time, we would have liked to explore the impact of the IX38′s design on the overclockability of the QX6850, but multiple condensation issues necessitated a halt of further testing. In terms of our setup, we had to remove some of the sinks from the IX38 to give vertical clearance for the Cryo-Z’s evap head. We chose to actively cool the MOSFETs, northbridge and memory to ensure stability.
The video cards were water cooled using Swiftech MCW60 blocks, a Thermochill PA120.3, a Swiftech MCP655 pump and the power of a bucket.
Lastly, our QX6850 was an engineering sample, and as such is not something that would generally be available for resale. A cursory search of Ebay yielded a few results for those with deep wallets and as much trust as money.
Specifications of the OCZ Cryo-Z
The system comes equipped with R-507A refrigerant (known as “Forane” or “Suva”) which is a 50/50 mixture of R-125 and R-134a. This is a superior design decision, as Forane is a much better refrigerant than many of the plausible alternatives and slightly better than the R-404A used by the competing Prometia Mach II GT. The gas is stored in a tank which dominates the unit’s interior. The remainder of the unit’s real estate yielding to a small fan/rad combo, a ZEL GQY70AD compressor, and the electronics.
As stated, the unit runs just over fifty pounds and measures 18.0″ x 8.2″ x 10.1″ (DxWxH). OCZ decision to support not only Socket AM2 and 775, but 754, 939 and 940 as well is a lovely nod to the enthusiast community. While we can’t imagine anyone who’d drop the bones on a Cryo-Z to achieve stratospheric Sempron overclocks, the decision is nontheless thoughtful and was well-received. Also included in the kit is a resistive heater which, when coupled with a motherboard’s backplate, keeps the PCB from literally freezing.
OCZ has also included closed-cel insulation foam in with the Cryo-Z, and rounds out their offering with the documentation and assorted mounting hardware. We would have liked to see OCZ include dielectric grease to insulate the CPU socket, but anyone considering phase-change cooling should have no trouble coming up with some of their own.
Similar to other phase change units, the Cryo-Z wrests control of the boot sequence from the motherboard. When you press the power switch on your PC, the Cryo-Z takes over and postpones the boot until the evap head achieves -30°C, and then boots the system. In reverse, the Cryo-Z has the capability of initiating a shutdown sequence on your PC if the temperature of the head rises too far while in operation. Lastly, an LCD on the face of the Cryo-Z unit allows you to monitor the temperature of the head.
Results and impressions
As previously indicated, we ran into some condensation issues. Primarily, moisture had begun to form on the back of the chip which eventually caused a hard shutdown of our system. We also had condensation issues on the top of the evap head. The head protrudes approximately two inches from the top of the block in a copper ring. This copper ring connects to the tube which feeds liquid R-507A, and gets as cold as the contact plate of the head itself. Typically, the looming which conceals the tube and the Cryo-Z’s boot-control wiring terminates in a heat-shrunk sheath which seals this ring. However, the seal had come undone. As a result, condensation was forming on the ring and dripping down into the socket area.
In spite of this, the system hovered around -55°C under load and often approached -60°C at 4.68GHz (14×333) using a 1.75v VCORE. This setting was unstable under load. Unfortunately, we were unable to determine whether the chip or the five phase PWM of the IX38 QuadGT was the culprit. Further attempts to fine-tune our efforts was hampered by condensation; fearing for the safety of our hardware, we aborted when our system simply shut off on us.
We are convinced, however, that the Cryo-Z unit could take a G0 quad to 5GHz with a better board and a good chip flying wingman. With a Yorkfield in the socket, 5GHz would probably have been a relative walk in the park to achieve.
The most obvious flaw in the Cryo-Z’s design is the poor quality of the LCD, which has abysmal viewing angles and an even worse response time. At a glance, we often found the panel hard to read. We would appreciate a more fluid display, but we’ve come to understand that the first generation of retail releases are already in the warehouse. Perhaps a future revision of the unit will correct this irritation.
Justifiably, we are most concerned by the seal at the top of the evap head coming undone. Were our motherboard installed vertically in a case, the moisture on the ring would have leaked into the socket area and continued down onto the primary Radeon 3870. Thankfully, we have been assured that this is not typical. End-users should not expect to see any such defect in their product. Given our experience with other OCZ products and understanding OCZ’s product quality philosophy, this is an assurance we accept.
Drawing to a close
While technical issues hampered a more thorough investigation of the unit’s prowess, we were impressed by the cooling potential of the unit. In our opinion, it is superior to the phase-change heavyweight, the Prometia Mach II GT. If OCZ can rein in the easily-corrected QC issues, the $299 MSRP of the OCZ Cryo-Z promises to send hard-core overclockers into a frenzy.
We are told that when the unit launches (“very soon”) it will be available directly at OCZ.com.
Last but not least, we would like to thank OCZ for giving us the opportunity to tinker with a final retail sample of their product, and for generously providing a test bench we could poke and prod at our leisure.