Radeon X1900 XTX 512MB (650/1550MHz)

The following photographs show the coolers installed on the Radeon X1900 XTX card:

Standard cooling system

Zalman VF700-Cu

Zalman VF900-Cu LED

Va-Aqua (RL-VNC-CNU1) water-cooling unit

Note that the Zalman VF700-Cu installs on the Radeon X1900 XTX in such a way that its fan covers almost all of the graphics memory chips whereas the Zalman VF900-Cu LED is installed somewhat higher and even goes beyond the top edge of the graphics card. The Va-Aqua water-block doesn’t cover anything other than the graphics core and doesn’t air-cool the PCB at all.

Here are the results of this test:

Well, there’s not much practical value in the results of the Radeon X1900 XTX’s stock cooler at its full speed. It does cool the GPU very well, but the noise from the plastic blower rotating at 5100rpm is just unbearable.

Comparing the other coolers, you may note again that the Zalman VF900-Cu LED cools the GPU as efficiently in the silent mode as the Zalman VF700-Cu at the maximum fan speed. And again there is not much improvement from increasing the fan speed of the new Zalman cooler. I should confess that the GPU temperature is still rather high despite the use of heat pipes in the VF900-Cu LED’s heatsink.

I think that the Aquagate liquid cooling system is the only cooler participating in this test that ensures comfortable conditions for the GPU of the Radeon X1900 XTX. It keeps the GPU temperature below 65°C (and I ran the 3DMark06 test for 25 rather than 10 times for this cooler since a liquid cooling system takes some time before the liquid warms up). You should be aware that the water-block cools the GPU only, but the memory chips and the PCB of the graphics card are not cooled because the Aquagate lacks a fan.

So, what about the PCB temperature? The readings of two temperature monitoring sensors of the Radeon X1900 XTX will help us see that.

It might have been expected that the temperature of the card in general and of its voltage regulator in particular is going to be high with the liquid cooling system due to the lack of any air stream to cool them. The high temperature with the new VF900-Cu LED is somewhat alarming. I guess it’s the position of the cooler (high up the card) that affected the temperature of the power circuit and the PCB. This is indirectly confirmed by the results of the Zalman VF700-Cu which easily wins these tests.

So, is the new Zalman cooler worse than the older model when it comes to cooling a top-end graphics card? Not quite. It’s the practical result that’s important, so I tried to overclock the Radeon X1900 XTX using both the Zalman coolers. And I found the Zalman VF900-Cu capable of keeping the Radeon X1900 XTX up and running at 680MHz GPU and 1630 memory frequencies (with a core voltage of 1.55V), even though the GPU temperature was as high as 98°C. With the Zalman VF700-Cu, the GPU clock rate of 670MHz was the maximum and the system would hang up if it was set higher (with or without a voltage increase). It looks like the cooling of the core is more important for the Radeon X1900 XTX than the cooling of the card’s PCB or voltage regulator. This may be different with other graphics card models, though.