Diamond Viper X1900XT 7

Diamond Viper X1900XT Review

Hotkey Poller & ATITool »

Introduction to Overclocking

Overclocking the X1x00 series cards is a little different from older generation cards. The cards have more options, and can be easier in certain ways to overclock, but more complex in others. With options to adjust voltages, there is little need to do "hardmods" to the cards in order to gain the extra juice needed for that nice overclock you dream of. For most enthusiasts the attention is now focused on cooling.

The basics of video card overclocking should be known before jumping into overclocking of these cards. For anyone that is unfamiliar with overclocking with ATITool, you should take a look here or use it as a reference guide.

When it comes to overclocking the X1900 series, there are numerous choices of software you can use. Some of the main ones being: ATITool, Rivatuner, and also the one built directly into Catalyst Control Center (CCC). ATITool will be our choice to use for overclocking.

2D and 3D Modes of the X1900

The X1x00 series uses similar techniques as NVIDIA with the clocks - this is the 2D and 3D clocks of the card. Simply put, 2D clocks are clocks of the card that are used while you’re using 2D graphics. For example, surfing the web, or viewing pictures. As we all know, viewing pictures is not a very “graphic intensive” process. 3D clocks are used in 3D applications, like games, or other video rendering programs.

This system of having 2D/3D clocks was introduced to help with power consumption, where 2D/3D clocks use separate frequencies and voltages. When you enter a 3D application, and the card is put to work, it will switch over to the higher 3D clocks in order to render the graphics efficiently and give better performance. You can think of 2D and 3D clocks as a profile - When a 3D application is loaded, the card loads the core clocks, memory clocks, and voltages used in 3D applications, hence the name "3D clocks".

Here you can see the frequencies changing over as the card requires the additional power during a 3DMark benchmark. As the benchmark runs you can see the card kick in the 3d clocks and as 3DMark pauses to load the next benchmark it drops to 2D clocks. This clock shifting during the 3DMark benchmarks explains why you score 300 to 400 points higher using ATITool. The clocks speeds in pictures below show the core and memory speeds do not change when using ATITool.

The issue that arises with the X1x00 series cards is it's a lot trickier for programmers to write overclocking tools. They have to consider both 2D and 3D clocks when it comes to the tool. However, there is a way around this issue.

Background Services & Drivers

As mentioned before, there are no applications out to control both 2D and 3D frequencies on ATI cards yet. Certain background applications control the drivers of the card for switching of 2D/3D profiles. Here are a few background services that affect the operation of the X1900 video cards.
  • Ati2evxx.exe – This service enables the 2D and 3D clocks to be separate from each other. This allows the 3D clocks to be used while running a 3D application. By disabling all instances of this, there will be no split 2D/3D clocks, which causes only 2D clocks to be used.

  • ATI HotKey Poller – By disabling this service, it will have the same effect as ending the Ati2evxx.exe instances, but will be permanent. There will be no need to end the Ati2evxx.exe instances. This also disables Overdrive in CCC and fixes the low temperature Windows shutdown issue.

  • OverClocker.exe - Relaxes the memory timings when overclocking the memory. This in return allows for higher clocks on the memory, but, looser timings.
When you load ATITool, it will close all running instances of Ati2evxx.exe, which in return disables the 2D/3D clock split. With Ati2evxx.exe closed, only 2D clocks will be used, the card will not switch over to 3D clocks. When you're overclocking the X1900, you are only overclocking the 2D clocks, as the 3D clocks, or profile will never be used once the Atievxx.exe services or HotKey Poller is disabled.

ATITool prompt

If you have disabled the ATI HotKey Poller service, there is no need to click "Yes" on this prompt.

Here are the default settings for the X1900 series cards:

Video CardCore Frequency
Memory Frequency
Core Voltage
Memory Voltage
Radeon X1900XT 2D Mode500MHz600MHz1.175v2.086v
Radeon X1900XT 3D Mode625MHz725MHz1.425v2.086v
Radeon X1900XTX 2D Mode500MHz600MHz1.175v2.086v
Radeon X1900XTX 3D Mode650MHz775MHz1.425v2.086v

Upon disabling the ATI HotKey Poller service, you will run 2D clocks all the time. As you can see from the table above, 2D mode uses quite reduced frequencies. So you will have to set the clocks and voltages to the 3D mode defaults to get the card back up to speed for 3D applications. After doing so, the real overclocking can be done.
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