Nvidia nForce 590 SLI User manual

User Guide
NVIDIA nForce 590 SLI
Technology Chipset Overclocking
May 2005
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Document Change History
Version Date Responsible Reason for Change
01 05/17/06 WZ, TS, NSmith Initial release.

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Table of Contents
NVIDIA nForce 590 SLI Technology Chipset Overclocking ...........................................1
Key Concepts.........................................................................................................2
Cooling...............................................................................................................2
Power Supply Units .............................................................................................2
Glossary of Terms ..................................................................................................3
Overclocking the NVIDIA nForce 590 SLI Technology Chipset......................................5
Disable AMD Cool’n’Quiet Technology......................................................................7
A Systematic Approach...........................................................................................8
CPU Reference Clock...........................................................................................9
CPU HyperTransport Overclocking......................................................................15
CPU Core Clock.................................................................................................17
DDR2 Memory Interface Overclocking ................................................................19
Balance CPU Frequency, HyperTransport, and Memory Overclocking Results ........24
PCI Express Overclocking ..................................................................................25
NVIDIA nForce 590 SLI MCP HyperTransport Interface........................................27
GPU Overclocking..............................................................................................29
Overclocking the System.......................................................................................30
Final Thoughts.........................................................................................................33

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List of Figures
Figure 1. High-level System Diagram.....................................................................6
Figure 2. Power Management Setup SBIOS Menu ..................................................7
Figure 3. System Clock Setup for CPU Reference Clock Overclocking.....................10
Figure 4. Memory Settings for CPU Reference Clock Overclocking.........................11
Figure 5. System Voltages for Reference Clock Overclocking.................................12
Figure 6. Adjusting CPU Reference Clock using NVIDIA nTune 5.0........................13
Figure 7. NVIDIA nTune 5.0 Stability Test ...........................................................14
Figure 8. System Clocks BIOS Configuration for CPU HTT Overclocking.................15
Figure 9. Adjusting HT Bus Frequency Using NVIDIA nTune 5.0 ...........................16
Figure 10. BIOS System Clocks Configuration for CPU Overclocking........................18
Figure 11. Disabling SLI-Ready Memory in BIOS....................................................20
Figure 12. BIOS System Voltages Configuration for Memory Overclocking...............20
Figure 13. BIOS Memory Timings Settings for Memory Overclocking.......................21
Figure 14. BIOS Drive Strength Setting for Memory Overclocking ...........................22
Figure 15. Memory Overclocking using NVIDIA nTune 5.0......................................23
Figure 16. Overclocking PCI Express using NVIDIA nTune 5.0 ................................26
Figure 17. BIOS System Voltages Configuration for MCP HTT Overclocking .............27
Figure 18. Adjusting MCP HTT Frequency in BIOS..................................................28
Figure 19. Overclocking GPU using NVIDIA nTune 5.0 ...........................................29
Figure 20. NVIDIA nTune 5.0 Dynamic BIOS Access ..............................................31
Figure 21. Storing Profiles in NVIDIA nTune 5.0 ....................................................32
Figure 22. Loading Automated Settings Using NVIDIA nTune 5.0 Custom Rules.......32

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NVIDIA nForce 590 SLI Technology
Chipset Overclocking
The purpose of this document is to guide users through overclocking NVIDIA
nForce 590 SLI technology chipset and use of the numerous tools and features that
will boost system performance, enhancing end-user gaming experience.
Overclocking PCs was once quite difficult and required people to physically change
hardware. In the past, companies that designed motherboards, CPUs, memory, and
graphics processor units were not supportive of overclocking nor were they
supportive of allowing users to tamper with qualified and tested settings.
Things have changed recently, however. Companies are more accommodating of
the urgent requests PC enthusiasts make. In fact, ASIC designers now incorporate a
lot of performance and overclocking headroom in the chips they produce.
Nowadays, with the availability of highly overclockable PC components and the
utilities that allow users to easily attain higher performance, overclocking has moved
into the mainstream.
NVIDIA®GPUs have enjoyed good reputations as products that are highly
overclockable. These products have provided higher performance for PC gaming
enthusiasts searching for the ultimate gaming experience.
NVIDIA specifically designed the NVIDIA nForce®590 SLI™technology chipset,
based on the new AMD AM2 Athlon processor, with overclocking enthusiasts in
mind. Even though the chipset itself is highly overclockable, NVIDIA built an
entire support platform around the NVIDIA nForce 590 SLI core logic. This
platform includes:
Software utilities such as the newly redesigned NVIDIA nTune 5.0 and its
highly sophisticated SBIOS
Special high-performance memory with Enhanced Performance Profiles
Technology
Recommended CPU coolers
NVIDIA SLI™technology.

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Key Concepts
Overclocking refers to operating PC components beyond what the manufacturer
guarantees. When overclocking is not carried on with care, it may lead to system
instability, crashes and loss of data, and may even destroy components. However,
when overclocking is performed attentively, it increases overall system performance
quite dramatically.
Cooling
Cooling PC components sufficiently is critical to overclocking. Keeping the CPU,
GPU, or overall system cool all contribute to overall system overclockability.
Otherwise, higher component temperatures lead to operation instability and
increased power consumption.
Theoretically, frequency is directly proportional to power and temperature. The
higher the frequency, the more the power consumed and the hotter the device
becomes. In order to achieve higher frequencies, component temperatures should
be kept as low as possible. With proper cooling, overclocking is highly attainable.
The most commonly cooling techniques are air cooling with fan-mounted heat sinks
and water cooling blocks. Even though water cooling is harder to install, it achieves
higher overclockability in comparison to air cooling because it keeps temperatures
lower. With technological advancements, air cooling has improved in performance
providing the means for overclocking. Even so, water cooling CPUs and GPUs is
becoming more widely accepted.
For NVIDIA recommended CPU coolers, visit www.SLIZone.com/nForce for a list of
components.
Power Supply Units
Power supply units are also important when it comes to overclocking. Increasing
system performance leads to increased power consumption by the overclocked
components. Having a power supply that generates enough power with headroom
is essential in guaranteeing system stability. Check the following site for a list of
power supplies suitable for SLI systems:
www.slizone.com/object/slizone2_build.html#certified_powersupplies.

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Glossary of Terms
3DMark Synthetic 3D benchmark that provides a measure of graphics
performance. It is also often used to test a system for stability.
AMD
Cool’n’Quiet™
Technology
Technology that changes CPU frequency dynamically depending
on power and thermal requirements of a CPU. Because it limits
the overclockability of an AMD CPU, it needs to be turned off
for best results.
For more information, visit this link http://www.amd.com/us-
en/Processors/ProductInformation/0,,30_118_9485_9487%5E10272,00.html.
BIOS Basic Input Output System.
CPU HTT HyperTransport interface connecting the AMD CPU to NVIDIA
nForce 590 SLI SPP. Nominally, it runs at 1 GHz clock or 4
GBps in downstream and upstream directions.
CPU HTT
Reference
Clock
Clock signal of the CPU HyperTransport link. It has impact on
HyperTransport bus speed, CPU frequency, as well as memory
frequency. It is 200 MHz nominally.
Multiplier Multiplier for your front-side bus (FSB). Multiply this value by the
speed of your FSB to get the end CPU clock speed:
CPU Clock Speed = Multiplier x FSB
Prime95 Program that searches for very large prime number. It contains
stability tests and is an indication of how robust a system is.
Serious Sam Video game which is used by overclockers to test system
robustness.
tRAS Row Address Strobe time is the amount of time between a row
being activated by precharge and deactivated. A row cannot be
deactivated until tRAS has completed. The lower tRAS is, the faster
the performance. If it is set too low, it can cause data corruption
by deactivating the row too soon.
tWR Write Recovery time is the memory timing that determines the
delay between a write command and when a precharge command
is set to the same bank of memory.
tWRRD W to R Termination Turnaround time is the number of clock
cycles between the last write data pair and the subsequent READ
command to the same physical bank.
tRCD RAS to CAS Access time is the amount of time in cycles for
issuing an active command and the read/write commands.

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tRRD RAS to RAS Delay is the amount of cycles that it takes to activate
the next bank of memory. The lower the timing, the better the
performance but it can cause instability.
tREF Refresh Rate is the amount of time it takes before a change is
refreshed. If the charge is not refreshed enough, the signal loses
its charge and corrupts data. It is measured in microseconds.
tRP Row Precharge time is the minimum time between active
commands and the read/writes of the next bank of the memory
module.
tRWT Read to Write Delay is when a write command is received, this is
the amount of cycles for the command to be executed.
tRDRD Read to Read Timing is the number of clock cycles between the
last read and the subsequent READ command to the same
physical bank.
tRC Row Cycle time is the minimum time in cycles it takes a row to
complete a full cycle. This can be determined by tRC = tRAS + tRP.
If tRC is set too short, it can cause data corruption. If tRC is set too
long, stability increases at the expense of performance.
tWTR Write to Read Delay is the amount of cycles required between a
valid write command and the next read command. Lower is
better performance but can cause instability.
tWRWR Write to Write time is the number of clock cycles between the last
write and the subsequent WRITE command to the same physical
bank.
tCL CAS latency is the number of clock cycles between the memory
receiving a READ command and actually starting to read
tCPC Command per Clock has only two values: 1 and 2. When set to 1,
it provides the best performance but limits memory frequency. In
order to overclock memory frequency, a value of 2 is more
reasonable.

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Overclocking the NVIDIA
nForce 590 SLI Technology Chipset
This section describes how to maximize the performance of an NVIDIA nForce
590 SLI PC system. It provides a systematic approach to unleashing its immense
performance potential. Bus speeds, bandwidth and processor core speeds — both
CPU and GPU core speeds — are the main contributing factors to boosting overall
system performance.
This section describes how to adjust settings for the major chip interconnects and
components that affect performance. Figure 1 shows a high-level diagram of
components in a PC system:
AMD Athlon CPU core frequency
DDR2 memory interface bandwidth and latency
CPU-NVIDIA nForce 590 SLI SPP HyperTransport bus
NVIDIA nForce 590 SLI SPP-NVIDIA nForce 590 SLI MCP
HyperTransport bus
NVIDIA nForce 590 SLI SPP/MCP PCI Express bus
GPU core and memory frequency

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Figure 1. High-level System Diagram

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Disable AMD Cool’n’Quiet
Technology
Before overclocking, disable the AMD Cool’n’Quiet™ technology.
The AMD Cool’n’Quiet technology must be disabled in order to enable stable
overclocking without limiting maximum achieved CPU performance. Use the
following procedure to disable this feature:
1. Set AMD Cool’n’Quiet to Disable on the Advanced Power Management
BIOS menu as shown in Figure 2.
Figure 2. Power Management Setup SBIOS Menu
2. Save the configuration.
3. Exit from the BIOS.

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A Systematic Approach
A step-by-step approach helps simplify the complex task of overclocking, described
in the following steps:
1. CPU reference clock (HTT)
2. CPU HyperTransport interface speed
3. CPU core clock frequency
4. DDR2 memory interface frequency & timing
5. Balance the results achieved with CPU frequency, HyperTransport, and
memory overclocking
6. Overclock the PCI Express x16 buses
7. Increase the NVIDIA nForce 590 SLI MCP HyperTransport bus frequency
8. Boost the GPU core and memory frequencies
Each of the following sections provides guidance on how to tweak an NVIDIA
nForce 590-SLI technology chipset based PC system based on this step-by-step
approach.
The first steps for overclocking the CPU reference clock, CPU HyperTransport bus,
CPU frequency, memory interface, PCI Express, and MCP HyperTransport link are
done in the SBIOS. Some system settings, such as CPU multiplier and memory
drive strength parameters, can only be adjusted in the SBIOS.
Once you use the SBIOS for an initial pass at overclocking, you then fine-tune the
settings with NVIDIA nTune 5.0. NVIDIA nTune provides flexibility to adjust
majority of parameters that affect overclocking in a Windows environment, allowing
for dynamic system overclocking and stability testing without the need for constant
system reboots.
Note: Start NVIDIA nTune 5.0 from Programs > NVIDIA Corporation >
nTune. Refer to the application’s on-line help for more information about
the nTune 5.0 features and settings.
The system configuration used in developing this guide is as follows:
CPU: AMD Athlon™ FX-62
Motherboard: Foxconn C51XEM2AA
Graphics: Dual NVIDIA GeForce 7900GTX SLI
CPU Cooler: Zalman CNPS9500AM2
Memory: Corsair TWIN2X2048-8500C5 with Enhanced
Performance Profiles (EPP) Technology

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CPU Reference Clock
CPU reference clock refers to the HyperTransport reference clock signal of the bus
connecting the CPU to NVIDIA nForce 590 SLI SPP chip. Typically, CPU
reference clock frequency is 200 MHz.
Updating the CPU reference clock requires several steps, described in this section:
1. Change system clocks in system BIOS menu.
2. Change memory timings in system BIOS menu.
3. Change system voltages in system BIOS menu.
4. Fine-tune the CPU reference clock in the motherboard settings control panel
of nTune.
5. Text the stability of the system
Because the CPU reference clock value direct impacts CPU core frequency and
HyperTransport bandwidth, take some time to determine the maximum attainable
CPU reference clock. To do so, use the following formulas:
CPU core frequency = CPU reference clock (MHz) ×CPU multiplier
HyperTransport bus speed = CPU reference clock (MHz) ×HT multiplier
Change System Clocks
Before you can find the maximum CPU reference clock the NVIDIA nForce 590
SLI motherboard is capable of achieving, you must make sure all reasons for
instability in the system are eliminated. Possible causes of instability include
undesirable values for CPU core clock, HyperTransport frequency, and memory
frequency. Make sure these are set well within their specifications in order to isolate
the root cause of issues that may arise from increasing the CPU reference clock
frequency.
When the system shows signs of instability, use the following procedure and the
BIOS menu shown in Figure 3 to reconfigure the system to better isolate the root
cause of issues:
1. Lower the CPU Multiplier to x9 (for FX-62 CPU, this value is sufficient; for
other AM2 CPUs x5 will work) in System Clocks BIOS menu.
2. Change CPU <-> nForce SPP multiplier to x3.
3. Set the Ref Clock (HTT) to 250 MHz as a starting point. You can fine-tune
the CPU reference clock later using nTune.

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Figure 3 shows the proper configuration in preparation for overclocking the CPU
reference clock.
Figure 3. System Clock Setup for CPU Reference Clock
Overclocking

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Set Memory Timings
Set memory frequency as low as possible from the Memory Timings BIOS menu, as
shown in Figure 4:
1. Set Timing Mode to [User limit].
2. Set Memory Clock Limit to [DDR2 400].
Figure 4. Memory Settings for CPU Reference Clock
Overclocking

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Change System Voltages
To enable increases in the CPU reference clock frequency, increase the following
voltages. Go to the System Voltages BIOS menu and change the following to
match the values shown in Figure 5:
1. Change CPU core voltage, CPU.
2. Change HyperTransport interface core voltage, HT CPU <-> nForce SPP.
3. Change NVIDIA nForce 590 SLI SPP and MCP core voltage, nForce SPP
and nForce MCP.
Figure 5. System Voltages for Reference Clock Overclocking
4. Save all BIOS settings.
5. Reboot to Windows.

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Fine-Tune CPU Reference Clock
Go to NVIDIA nTune 5.0 to adjust the frequency using the Reference Clock
(HTT) setting from NVIDIA nTune Motherboard Settings control panel as shown
in Figure 6. This action incrementally adjusts the reference clock and allows for
dynamically testing for system stability.
Figure 6. Adjusting CPU Reference Clock using NVIDIA
nTune 5.0
Tip: In nTune, use Left and Right keyboard buttons to make small increments
or decrements for the CPU Reference clock (HTT) slider value.
Incrementing voltages slightly can provide more overclockability.
A CPU reference clock value of 300 MHz is an achievable target, and in some cases
the interface can be overclocked much more depending on the speed of the AMD
FX-62 CPU and nForce 590 SPP chips. Chip speeds vary due to the manufacturing
process variations of the ASICs–application specific integrated circuits.

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Test System Stability
To test system stability, run the NVIDIA Stability Test for at least two hours as seen
in Figure 7. Additionally, running 3DMark, Prime95, or a GPU intensive game like
Serious Sam II for an extended period of time allows you to get a sense of overall
system stability.
Note: CPU reference clock values between 314 MHz to 320 MHz may not
provide system stability.
Figure 7. NVIDIA nTune 5.0 Stability Test

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CPU HyperTransport Overclocking
CPU HyperTransport (HTT) bandwidth (speed) is an important contributing factor
to overall system performance. Its nominal effective bandwidth is 4 GBps running
at 1 GHz (200 MHz × 5) upstream and downstream. CPU HTT bandwidth is
directly proportional to CPU reference clock as mentioned earlier in CPU Reference
Clock on page 9. It defines how fast data propagates between PC devices and CPU
and system memory to maximize throughput. Furthermore, CPU HTT bus speed
has a tremendous impact on memory performance.
Use the following procedure to overclock CPU HyperTransport bandwidth:
1. Eliminate all sources of instability by configuring System Clocks BIOS
settings as shown in Figure 8.
a) Lower the CPU Multiplier to x10 (for FX-62 CPU, this value is sufficient
and to be safe a x8 multiplier will work; for other AM2 CPUs x5 will
work) in System Clocks BIOS menu.
b) Change CPU <-> nForce SPP multiplier to x5.
c) Set the Ref Clock (HTT) to 200 MHz as a starting point. You can fine-
tune the CPU reference clock later using nTune.
Figure 8. System Clocks BIOS Configuration for CPU HTT
Overclocking
Note: In the Memory Timings BIOS menu, make sure Memory Clock Limit is set
to [DDR2 400] as shown in Figure 4.

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2. Go to NVIDIA nTune to incrementally adjust and test the CPU HTT bus in
Windows. Increasing the Reference clock (HTT) to 281 MHz provides a
stable setting that effectively increases the CPU HyperTransport speed by
40% to 1.4 GHz, up from 1 GHz. (Check in using the NVIDIA nTune
Motherboard Settings control panel shown in Figure 9).
The CPU HTT interface of NVIDIA nForce 590 SLI motherboards can
support much higher speeds. Adjusting the voltage can help you reach
increases of 50 to 60%.
You can achieve more overclocking by using better cooling systems or by
incrementing voltages slightly (both through the BIOS settings and nTune).
Remember that ASIC and board process variation affects the overclockability
of a system.
Figure 9. Adjusting HT Bus Frequency Using NVIDIA nTune
5.0
3. Run a Stability Test or another application (for example, 3DMark or Serious
Sam) to test system stability.