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ZM-WB5 Plus waterblock vitals

   ZM-WB5 Plus waterblock
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   18 May 2009
   Lawrence Latif

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Cool runnings
When Zalman released a new waterblock aimed at their Reserator watercooling system, we wondered if the four year old watercooling system could cope with the new Core i7 processor from Intel. We were pleasantly surprised.

The Reserator was Zalman's answer to providing enthusiasts an easy entry to the world of watercooling. Watercooling computers is nothing new and have traditionally been the reserve of performance junkies who use it to push their hardware to the limits. However the Reserator was a different kettle of fish, it wasn't there to push your hardware to the limits but provide an extremely quiet cooling solution.

With every iteration of the Reserator, extra water blocks were made available allowing the user to cool not only their CPU but the video card and motherboard chipset. However the centre of any Reserator cooled system was the radiator. Although later Reserator units went with a more traditional radiator, the Reserator 1 and it's different incarnations came with what can only be described an aluminium finned tower. Taller than most mid-tower cases, the size was vital as it was designed to be operated without the aid of a fan, though one was later added to increase its cooling capabilities.

With a small 5W Eheim pump submerged in the belly of the radiator and no cooling fan, the Reserator was silent from a metre away. Watercooling enthusiasts pointed to the use of 3/8" diameter pipes, the low throughput pump and the lack of fan on the radiator as a legitimate reasons for avoiding the Reserators, others, saw it as not only an easy route into watercooling but a way of cooling substantial computers, quietly. Newer waterblocks added support for AM2, AM2+ and LGA 775 processors. With the ZM-WB5 Plus the Reserator can now cool AM3 and LGA 1366 processors like everyone's current favourite, the Intel Core i7 920.

New kid on the block

The ZM-WB5 Plus is a modified version of the ZM-WB5 and continues the gun-metal colour, all metal construction. Gone are the plastic see-through covers and now we've got a copper based finished in shiny dark grey with a slightly lighter aluminium cover. The barbs are pre-attached and accept a number of different tube sizes including 14x10, 13x10, 13x9, 12x9, 12x8, 11x8 and 10x8mm (outer x inner diameter). We tested using 10x8mm as this is what came with our Reserator 1 v2 kit some years back.

Click to enlargeSo why exactly are we so excited about a waterblock? Well, Intel's Core i7 processor has almost universally be lauded as the must have platform upgrade not just because of raw speed but the overclockability of the bottom of the rung i7 920 processor. Factory clocked at 2.66GHz, many enthusiasts have hit 3.5GHz and beyond with the latest D0 stepping processor available from retailers such as Scan promising better chances [1, 2] of hitting these extreme speeds. Now, can a quiet cooler designed for silence be able to live with the heat generated at these speeds by a processor having a maximum TDP of 130W before we apply voltage increases?

Playing it cool

First we have a few bits of housekeeping to sort out. The performance of any watercooling system depends greatly on what components are in the "loop". Add other heat sources such as a video card and you're going to need to beef up your radiator and pump. As we were purposefully looking to overclock the processor, we decided to put the NVIDIA 8800GTX video card on a separate loop connected to a different Reserator radiator/pump system. Judging by the surface temperature of that radiator this was a pretty good decision. However if you have a 65W TDP processor such as Intel Core2Duo units based on the "Wolfdale" core, then we found a single Reserator managed to keep up with the demands of both heat sources when being run flat out.

Getting the formalities out of the way, at 2.66GHz the Reserator and ZM-WB5 Plus block copes just fine. With temperatures around the 47-52C range and the radiator only moderately warm things were looking good for some overclocking action. For those looking run a Core i7 920 at default speeds quietly, there's nothing stopping us from recommending the Reserator 1 and it's variants.

Overclocking Core i7 processors is slightly different from just upping the front side bus, however it's far from being complicated and the basic adjustments are the FSB (known as the BLCK), CPU and the memory/QPI voltage. Many report that disabling HyperThreading and Turbo modes have helped them reach higher frequencies. With three sticks of Corsair PC-12800 DDR 3 memory, we hoped that it would not be the limiting factor. Also with retailers offering the new D0 stepping Core i7 920 we coupled it to the Asus P6T X58 motherboard and went in search of some free performance.

We cranked the FSB up to 200MHz and upped the core voltage to 1.4v and the QPI to 1.5v, Hyperthreading was not disabled but Turbo mode and Speedstep frequency scaling were. With a 4GHz processor and our DDR 3 running at just under 1600MHz we managed to load Windows Vista but not much else. Prime95's torture test would run for seconds before the system rebooted.

Slightly disappointed that we couldn’t hit the 4.0GHz mark, the BLCK was lowered to 190MHz, producing an overall frequency of 3.8GHz. At these settings we managed to run Prime95 for six hours without any trouble. The Reserator's radiator did get uncomfortably hot and temperatures were in the late 80s but it managed to live with the heat being generated by the Core i7 920. As overclocking isn't an exact science your mileage will vary on the processor you get and by all means this wasn't a completely conclusive overclocking session. We tinkered with settings for a couple of days with long tests in between but there are a plethora of settings waiting to be adjusted which may herald further performance gains.

The one caveat to all this is that the CPU was the only heat source connected to the watercooling loop. If you are thinking of running a high-end video card we would strongly suggest considering another watercooling loop or active cooling.

Zalman's ZM-WB5 Plus waterblock gives the old Reserator 1 a new lease of life. Not only can it cope with Intel's Core i7 but produce respectable performance when the processor is pushed to its limits. With QuietPC selling the ZM-WB5 Plus for £33 it really is a case of Zalman being able to teach an old dog new tricks. If you have a Reserator and are thinking of upgrading, silent cooling can be had for the right end of 35 quid in the form of the ZM-WB5 plus.



[1] Key, G. - Intel Core i7 920 D0 Stepping - Preview, Anandtech
[2] Worrel, J. - First Core i7 920 D0 overclock results are promising, Fudzilla