GTJ's ®® 975XBX2 Bad Axe 2 Guide

Introduction Tool, Driver and Information Links Definitions Hardware Notes BIOS Notes OS Compatability

Introduction

WORK IN PROGRESS This guide is really a collection of notes for the Intel 975XBX2 Motherboard. It's certainly not exhaustive and it's not meant to be a review of the board. Comments and corrections welcome.e.

Tool, Driver and Information Links

Intel 975 XBX2 Homepage

Intel 975XBX2 Current Downloads

Intel 975XBX2 Previous BIOS releases

Intel Matrix Storage Manager The drivers and management console from the page are usually newer than the ones on the XBX2 downloads page.

Intel Processor Support Descriptions and documentation for Intel's processor lines.

Intel 975X Express Chipset Support Description and documentation.

Everest The best all around monitoring program. Full support for the XBX2. Get the Latest BETA then buy a license.

RMClock Excellent tool for manipulating power and thermal management features

Speedfan ThThe latest version has full suport for the XBX2 and will allow you to control the fan speeds.

CPU-Z

CrystalCPUID

MemTest86+ THE memory testing standard.

CoreTemp Version 0.95 has a feature to show you the delta to TJUNCTION. See Temperature Sensing below.

Intel Desktop Control Center Has issues with other monitoring programs.

Intel Desktop Utilities

Definitions:

MCH: Intel 82975X Memory Controllller Hub: AKA Northbound Chipset (NB) ICH: Intel 82801GR ICH7R I/O Controller Hub: AKA Southbound Chipset (SB) QDR: Quad Data Rate or Quad Pumped: Data passes at 4 times the clock frequency DDR: Double Data Rate: Data passes at 2 times the clock frequency MT/s: Mega Transfers per Second: Intel uses this term to describe the rate at which data passes on the FSB. In this context, each transfer is 64 bits or 8 bytes. VRD: -Down: A voltage regulator circuit mounted on a motherboard. Also a specification for controlling the regulator, currently version 11.0. VID: Voltage Identification: A code supplied by the processor the detemines the reference output voltage to be delivered back to the processor. TDP: Thermal Design Power: Intel defines TDP as "A power dissipation target based on worst-case applications. Thermal solutions should be designed to dissipate the thermal design power". TM: Thermal Monitor: Intel defines TM as "A feature on the processor that attempts to keep the temperature within factory specifications". TCC: Thermal Control Circuit: Intel defines TCC as "Thermal Monitor uses the TCC to reduce die temperatures by lowering effective processor frequency when the die has exceeded its operating limits". C1E: Enhanced Halt State: A processor feature that lets it automatically lower the processor multiplier or voltage when idle. EIST: Enhanced Intel Speedstep Technology: Does the same thing as C1E except under operating system or user control TIM: Thermal Interface Material: Heatsink compound, thermal grease, thermal tape, etc. HSF: Heatsink Fan assembly. IHS: Integrated Heat Spreader: Picture DTS: Digital Thermal Sensor TCONTROL The temperature at which the TCC is activated TJUNCTION The temperature reported by the DTS TJMAX The maximum allowed TJUNCION

Hardware Notes

Temperature Sensing

The XBX2 provides 3 temeprature sensors accessable via the Andigilog aSC7621 hardware monitoring chip. The "CPU" sensor is actually located on the CPU (go figure) but is read by the aSC7621. This sensor is not to be confused with the "Core" sensors (more later). The "Motherboard" or "System Zone 1" sensor is the aSC7621 itself. The "DIMM" or "System Zone 2" sensor is located between the DIMM slots. See this picture for their exact locations: Temperature sensor locations. These 3 temps are available on the BIOS HW Monitoring menu as well as IDCC, IDU, and several other third party monitoring programs.

Beginning with the Core series processors, Intel also provides a highly accurate Digital Thermal Sensor located in each of the processor cores. These "Core" temps are the best source of information when overclocking but unfortunately, Intel threw a monkey wrench into the works by making the process of reading those temps a little convoluted...

Intel processors have a temperature at which the Thermal Control Circuit is activated called TCONTROL or TJMAX or sometimes (incorrectly) TJUNCTION. This temperature varies by processor family. For Core 2 Duo E6000 series processors, for instance, it's 85°C. For others it may be 100°C. The DTS reports its temps relative to that temperature. The problem is that Intel didn't provide an accurate way to programatically determine that starting point; you have to "know" it. Some temperature monitoring programs use undocumented processor registers to determine TCONTROL and others use a simple hard coded lookup table to determine it. Neither one is going to be 100% accurate. A dead giveaway that there's a problem is when, with your processors at idle, the "core" temps are about 15°C different from the "CPU" temp.

Voltage

The aSC7621 hardware monitoring chip also monitors 5 voltages: the standard 12v, 5v, and 3.3v supplies that do the bulk of the non-cpu work, and VCORE and VMCH (sometimes labelled simply 1.5v). The monitor is fairly accurate and will probably show the VCORE and VMCH slightly lower that set via BIOS. This is a normal artifact of digitally controlled voltage regulators. While VMCH should remain constant, the VCORE will probably change in response to power saving features like C1E and EIST. The VCORE can also change due to a phenomenon known as Vdroop. This is basically a "brownout" situation where the VRD can't supply the required voltage under extreme load. A certain amount of Vdroop is normal and, although I can't verify this, it's said that the XBX2 has one of the lowest Vdroops around.

There does not seem to be a way to monitor the memory voltage other than with a multimeter. You can do so by probing here: Memory Voltage measuring point. You can also measure VCORE and VMCH: CPU Core Voltage measuring point and MCH Core Voltage measuring point. Measure safely please. The voltages themselves aren't dangerous but an X6800 processor, for instance, can draw 90 amps. Short that to ground and the least of your problems will be getting a new board.

Cooling

If you're planning on overclocking, you won't get much headroom out of the stock Intel HSF. I don't remember seeing any reports of aftermarket processor coolers that don't fit on the board but your case has a lot to do with it of course. For the MCH, if you have good airflow through the case you might not have to do anything more than replace the TIM. Getting the MCH heatsink off takes about 10 seconds with no tools. You just spread the fins that hold the black retaining brackets and rotate the brackets outward. If you want silence or extreme cooling, the Swiftech MCW30 waterblock fits fine, as do several others. A small fan can also be used and there's a 5th fan header right next to the MCH for that purpose. For the ICH, don't bother. It's pretty much isolated from overclocking effects and doesn't put out enough heat to worry about. Don't even bother replacing the TIM. The ICH heatsink is much more firmly attached to the chip and if you're not careful you can cause some damage getting it off.

There are 5 fan headers on the board, all marked on the cheat-sheets that come with the board. The 5th fan header (MCH) is neither monitorable not controllable. The remaining 4 are both monitorable and controllable. Speaking of which, there are 3 fan speed control channels: 1 for CPU, 1 for AUX, and the 3rd controls both the front and rear fans. The CPU and AUX headers are the new 4-pin type, not to be confused with the old 4 pin hard-drive type Molex connectors. You can plug 3-pin fans into them but you won't get speed control.

Both IDCC and Speedfan can control the fan speeds but you have to disable automatic control first. It's obvious in IDCC but in Speedfan, you have to go to Configure, Advanced and set the PWM output to manual.

Oh yeah, that 4 pin hard-drive type Molex connector on the motherboard isn't meant to supply a fan. It's there to receive additional power for video cards that don't have their own PCI-e power connector.

BIOS Notes

As of 3/30/2007, BIOS 2333 still seems to be the favorite. It does have a bug where the case HDD light stays on if you disable the Marvell SATA Controller but many people claim it's the "stablest". The HDD light bug was fixed a few releases later. I've been running the latest BIOS (2674 as of today) without problems.

Storage

There are 2 SATA controllers on this board. The Intel ICH7R itself contains a 4 port RAID0/1/5/10 controller (black ports) plus there's a Marvell 88SE6145 4 port RAID0/1/10 controller (red/blue ports) attached to the ICH7R as a PCI-e device. The Intel controller has a slight performance advantage since it's embedded in the ICH7R plus it supports RAID5 which the Marvell doesn't. It also operates in several modes and you must decide which one you want to use before installing your OS.

IDE Emulates a standard IDE controller. No special drivers needed but also doesn't support RAID or Native Command Queueing (NCQ). AHCI Advanced Host Controller Interface. Designed for SATA and can give a slight performance boost over IDE. Doesn't support RAID but does support NCQ. Vista and Linux have standard drivers for AHCI, earlier Windows OSes don't. RAID Full support for both RAID and non-RAID configurations. Like AHCI, Vista has the proper driver, but earlier Windows OSes will need the F6 diskette during setup. In this mode, Linux will recognize the controller as a standard AHCI controller; you can use single disks but not RAID arrays. This is the mode I recommend because it does everything the others do. Remember, Windows does NOT like to have the mass storage controller changed out from under it so even if you don't plan to use RAID in the short term, if you don't set it now, you'll never be able to set it without a Windows reinstall. The ICH7R platform (Intel Matrix Storage Management) is used by many motherboards, both from Intel and other manufacturers and Intel has a web page specifically for it. See the links above.

The Marvell controller isn't supported natively by any OS at this time but Intel provides Windows drivers. If you don't use the Marvell controller, disable "Secondary SATA Controller" on the Advanced, Peripheral BIOS page.

Both the Intel and Marvell driver packages contain management consoles that run from Windows. You really only need the drivers so don't bother with the consoles if you're short on time and space. Everything you can do from them you can also do from the BIOS screens.

One other note: Whenever you create or delete an array, reboot back into the board's BIOS screens and check the boot order. They sometimes get rearranged when you mess with the arrays.

Final Reminder: Once you install Windows, do NOT change the Intel SATA Controller mode. If you do you won't be able to boot.

Power Management

Both C1E and EIST are supported by the board. C1E is on the hidden maintenance menu so you'll have to use the config jumper to get to it. EIST is on the Power menu. Both do the same thing essentially: lower the multiplier and VCORE when the processor is idle. C1E allows the processor to do it automatically. EIST allows the operating system (or the user) to do it. Both are "good" things in the long run but can be very confusing if you're seeing your multiplier and voltage change on their own while you're trying to debug an overclock. To make matters more confusing, as of BIOS 2674, there's a bug that's not actually turning C1E off when you disable it in the BIOS. Both Everest and RMClock allow you to turn it off from Windows though. There's also another little C1E behavior that you should be aware of. If you change your VCORE to something other than the default, C1E will only reduce the multipler and not the voltage.

Speaking of changing VCORE, boards earlier than 505 may have an issue where changing any of the voltages in BIOS will not take effect unless the board is completely powered off and back on again. I.E. Pull the plug or switch off the PSU until the green power LED by the memory goes out. This is less a problem with rev 505 boards but I've still had to do the hard power cycle occasionally. Be safe: always hard power cycle when you change voltages.

Watchdog

The watchdog was introduced to the maintenance menu shortly after the 2333 BIOS release. It's supposed to allow an easy recovery from a failed overclock attempt but as of BIOS 2674, it consideres any change to the VCORE to be a failed overclock attempt. If you change your VCORE and don't disable the watchdog, you'll be stuck in an endless loop of "failed to POST" messages.

Other notes:

Advanced, Boot Configuration: Turn on the fan controls to have the system automatically change the fan speeds based on temeprature. Performance, Processor Overrides: Turn Enhanced Power Slope on even if you don't plan on overlcocking. It allows additional current to be provided to the processor when needed. Security: XD Technology is Execute Bit Disable and is a good security feature. VT technology is Virtualization (or Vanderpool) support. Unless you're running VMWare or another virtualization product, disable it. leaving it on doesn't hurt anything though.

Config Jumper

The jumper that puts the BIOS in recovery or maintenance mode is not easily accesssible once the motherboard is mounted and all the cables connected, especially is you have a long video card. To make it easier to change the jumper use a 3-pin fan extension cable like the ones that come with fan controllers. Plug one end into the motherboard header and put the jumper on the other end. See this picture for an idea. Just don't accidentally plug it into a fan header, :). If you're handy with a soldering iron, you can wire up a SPDT Center-Off switch and mount it through the back of the case. If you don't know what a "SPDT Center-Off" switch is, then you're probably NOT handy with a soldering iron either. :)

Overclocking

Block Diagram: Intel 975X Express Chipset

Background

Speed

Processor speed is determined simply enough: multiply the FSB in MHz by the processor's multiplier. To change the speed, you can change either one or the other. Unfortunately as of the current BIOS (v2674) you only have the option to change the multiplier on a small subset of processor models (Engineering Samples and the Extreme series I believe). That means that changing the FSB speed is going to be the most likely avenue of processor overclocking.

The FSB between the CPU and MCH is QDR and 8 bytes wide. That means that binary data passes on the bus at 4 times the clock frequency and since the bus is 8 bytes wide, that's 32 bytes/clock cycle. I.E. If the FSB Clock Freq is set to 266 (the default) then the actual data rate is 1066 MT/s (the advertized FSB) or 8528 MB/s (266 * 32 or 1066 * 8).

The bus between the MCH and memory is dual channel, each DDR and 64 bits / 8 bytes wide. The actual frequency is controlled by the FSB frequency and the ratio of the BIOS Reference Frequency to BIOS Memory Frequency. It's important to note that Neither the Reference Frequency nor the Memory Frequency settings in the BIOS set actual frequencies. I'll say it a different way... setting the Memory Frequency in BIOS to a particular value does NOT necessarily set your memory to that frequency. It's the FSB frequency divided by the ratio of the 2 frequencies that sets your memory frequency. To make things a little more confusing, the Memory Frequency is set using the DDR2 equivalent not the actual bus clock frequency. Hence a Reference/Memory Frequency setting of 266/800 (the default) is 0.666 (266/400) or a 2:3 ratio. One other note before we get to some examples... Although the bus is actually 2 channels, real-world throughput isn't double that of a single channel. My own testing and other test results I've seen published suggest about a 30% throughput increase.

Example 1:

BIOS Settings: FSB=266, Reference Frequency=266, Memory Frequency=800 (all defaults)

FSB/MEM Ratio: (266 fREF / (800 fMEM / 2)) = 0.666 = 2/3 Memory Clock: (266 fFSB / 0.666) = 400 MHz DDR2 Equiv: (400 fMEMCLK * 2) = 800MHz = PC2-6400

FSB Throughput: (266 fFSB * 4 (QDR) * 8 (bytes)) = 8512 MB/s Single Channel Mem Throughput: (800 fDDR2 * 8 bytes) = 6400 MB/s Dual Channel Mem Throughput: (6400 * 2) = 12800 MB/s Real World Mem Throughput: (6400 + (6400 * .30)) = 8320 MB/s

This example represents the board's defaults if you're using DDR2-800 memory. You can't necessarily tell from the BIOS settings alone but this is actually a pretty balanced configuration. Look at the FSB throughput and the real-world memory thoughput. They're almost equal. I know I said earlier that the Memory Frequency BIOS setting doesn't actually set the frequency but in this case, the math works out such that it does.

Example 2:

BIOS Settings: FSB=320, Reference Frequency=266, Memory Frequency=667

FSB/MEM Ratio: (266 fREF / (667 fMEM / 2)) = 0.8 = 4/5 Memory Clock: (320 fFSB / 0.8) = 400 MHz DDR2 Equiv: (400 fMEMCLK * 2) = 800MHz = PC2-6400

FSB Throughput: (320 fFSB * 4 (QDR) * 8 (bytes)) = 10240 MB/s Single Channel Mem Throughput: (800 fDDR2 * 8 bytes) = 6400 MB/s Dual Channel Mem Throughput: (6400 * 2) = 12800 MB/s Real World Mem Throughput: (6400 + (6400 * .30)) = 8320 MB/s

This example has the FSB raised and the Memory Frequency lowered. Notice that while the ratio changed, the resulting memory clock remains at 400 MHz and the real-world memory throughput remains at 8320 MB/s. Look at the FSB throughput though. It's up to 10240 MB/s making it 23% higher than the memory throughput.

Example 3:

BIOS Settings: FSB=360, Reference Frequency=266, Memory Frequency=667

FSB/MEM Ratio: (266 fREF / (667 fMEM / 2)) = 0.8 = 4/5 Memory Clock: (360 fFSB / 0.8) = 450 MHz DDR2 Equiv: (450 fMEMCLK * 2) = 900 MHz = ~PC2-7200

FSB Throughput: (360 fFSB * 4 (QDR) * 8 (bytes)) = 11520 MB/s Single Channel Mem Throughput: (900 fDDR2 * 8 bytes) = 7200 MB/s Dual Channel Mem Throughput: (7200 * 2) = 14400 MB/s Real World Mem Throughput: (7200 + (7200 * .30)) = 9360 MB/s

If you're running a E6600 processor, this gets you about a 3.2 GHz clock. If you have memory rated at only DDR2-800, it's now overclocked but still doesn't give you thoughput to match the FSB.

Example 4:

BIOS Settings: FSB=360, Reference Frequency=266, Memory Frequency=800

FSB/MEM Ratio: (266 fREF / (800 fMEM / 2)) = 0.666 = 2/3 Memory Clock: (360 fFSB / 0.666) = 541 MHz DDR2 Equiv: (541 fMEMCLK * 2) = 1082 MHz = ~PC2-8000

FSB Throughput: (360 fFSB * 4 (QDR) * 8 (bytes)) = 11520 MB/s Single Channel Mem Throughput: (1082 fDDR2 * 8 bytes) = 8656 MB/s Dual Channel Mem Throughput: (8656 * 2) = 17312 MB/s Real World Mem Throughput: (8656 + (5760 * .30)) = 11252 MB/s

So we left the FSB at 360 MHz and used the same reference and memory frequencies as example 1 and we're back to comparable throughputs again. Look at the DDR2 speed though. You're going to have to clock your memory at DDR2-1000 or PC2-8000. This is a good case for buying the fastest memory you can afford.

You'll notice that in the examples, the Reference Frequency is left at 266 MHz. That's because it also performs a secondary function related to the MCH...

The MCH has internal timings just like your memory. It automatically adjusts those timings, tightening them or loosening them, based on how fast or slow you tell it that it's going to run. Again, like main memory, the faster you run, the looser the timings will have to be to maintain stability. It's called the "strap" presumably because it's akin to setting a jumper strap on the motherboard. In the XBX2's case, it's controlled by the Reference Frequency. When you pick a particular value, besides affecting the memory bus speed, you're also telling the MCH to use a particular set of internal timings. The strap is usually referred to in advertized FSB terms so setting the Reference Frequency to 266 is equivalent to setting the "1066 strap". The MCH then sets its internal timings to what it thinks is best for running at 266MHz. Like the Memory Frequency, this doesn't necessarily mean you're runinng at that speed. You're just telling the MCH to assume you are.

Use the XBX2 Memory Calculator to see how the settings relate.

Voltage

CPU: The CPU's core voltage is actually controlled by the CPU itself. During the manufacturing process, the CPU is programmed with its default VID which is going to be the voltage needed be stable at the CPU's rated speed. Usually it's on a label on the outside of the box. 1.3250v is a popular default. When the board powers on, the VRD delivers a minimum voltage to the CPU to get it to actually start, then the CPU sends back it's default VID and the VRD brings the voltage up to what was specified. During normal operation, the CPU can instruct the VRD to lower the voltage based on what power saving features are enabled (C1E, EIST) but the CPU will never instruct the VRD to increase the voltage above it's programmed VID. This presents a problem if you plan to increase the CPU speed beyond what it's rated for because you're probably going to need more voltage to be stable. To get around this, the board provides a "CPU Voltage Override" A.K.A. "Core Voltage", VCORE, Vcc, etc. Basically, it tells the VRD "when the CPU asks for its default VID (which is also its max VID), really give it this." So, if the CPU's default VID is 1.3250v and you have the override set to 1.4500, the VRD will deliver 1.4500v whenever the CPU asks for 1.3250v.

MCH: The MCH also has a core voltage the default of which is 1.525v. It may also need to be increased to maintain stability as its speed increases. This is a simple direct setting in the BIOS.

FSB: The FSB has a termination voltage which is required to insure accurate data delivery over the bus. Again, the higher the FSB speed, the higher the termination voltage will have to be. This is also a simple direct setting in the BIOS.

Memory: Yep, you guessed it. The higher the speed, the higher the voltage will have to be. This is also a simple direct setting in the BIOS.

Temperature

All that power has to go somewhere and that somewhere is your case in the form of thermal energy. Actually heat is a function of both voltage and speed so increasing BOTH increases the heat output even further. One forumla I found to calculate the heat produced by an overclocked CPU is (stock TDP * (new vcore2 / stock vcore2) * (new FSB speed / stock FSB speed)). Let's use a Core 2 Duo E6600 with a stock TDP of 65w as an example. We'll also use 1.500v and 400MHz as the overclocked settings. So, the new TDP is (65 * (1.500 2 / 1.3252) * (400 / 266)) = 125.2w. That's almost double the heat for a 50% overclock. I can't vouch for the technical accuracy of the formula but it makes sense.

The processor has several thermal protection features but don't rely on them to keep you out of trouble.

So now what?

Overclocking is a balancing act amongst your objectives, component capabilities, stability, temperature, speed, latency, etc. Nobody can give you a canned answer as to what's best. Here are some tidbits though...

Set reasonable objectives. Be methodical and take good notes. Only overclock 1 thing at a time. For instance, if you're overclocking the CPU, underclock the memory until you're sure that the CPU is stable. This way if there's a failure, you won't be guessing what caused the problem. WATCH YOUR TEMPERATURES! If your load temperatures start hitting the upper 60's it's time to re-think your objectives or your thermal solution. Disable the Watchdog. As of BIOS 2674, if you leave it enabled all attempts to increase your CPU voltage will result in failures to boot. Disable C1E while you're experimenting but re-enable it when you're stable. It's a GOOD thing long term. The 1066 strap (266 Reference Frequency) seems optimal. Unless you plan on running a FSB of 450 or higher, going higher on the strap will unnecessarily loosen the MCH timings and you probably won't even be able to boot on a strap of 800 or 533 unless you underclock. A 1:1 FSB to Memory ratio sounds nice but the critical comparison is FSB throughput to real-world memory throughput. Ideally, you want the 2 to be close. Always use the same set of tools and the same settings when testing your overclocks otherwise you won't be able to compare your results.

OS Compatability

Coming Soon. Intel, , Intel Core, Core Inside, Intel Inside, Intel Leap ahead, Intel SpeedStep and the Intel logo are trademarks or registered trademarks of Intel Corporation or its subsidiaries.