Overclocking Xeon X5482

[Pan_Melas]

Good day to all

This is my first message to this forum and I am glad to participate.

Although I understand that this is a really long topic, I would very much appreciate if the O/C experts read it carefully and - if and when possible - try to give me an advice.

I have to admit that I have not seriously been involved with overclocking, despite my intentions in the past, which remained just that: Intentions. Therefore, if I write any "stupid" words or phrases, I'd like to have moderators' understanding.

The main subject, now.
Short time ago (about two months) I purchased a - 2nd hand - Intel quad-core Xeon X5482 processor (3.2 GHz, 12MB cache, 1600 MHz FSB, Stepping SLANZ-150W max. TDP), of the Harpertown family. As we all know, Xeons of this family work on motherborads with socket LGA771. However, a relatively recent "modding" has become trendy. With a simple adaption, Xeons can work on motherboards with socket 775, provided that these motherboards are equipped with one of the advanced chipsets of the 775 platform (that is: Intel P45-P43-P35-P31-G45-G43-G41-G35-G33-G31, nForce 780i-750i-630i, GeForce 9400-9300). Motherboards with other, older or inferior chipsets, simply cannot see a Xeon in their BIOS. More details for this "modding" can someone find in several links, if someone "googles" with the key words: "LGA771 to LGA775". For example, one of these links is the following:

http://www.delidded.com/lga-771-to-775-adapter/

I have installed this CPU on a newer and advanced (for its time) motherboard with s775, the Gigabyte GA-EP45T-UD3R. It is a motherboard with DDR3 slots only (up to 16GB total memory capacity and up to 2200+ MHz - I am going to use 4 DIMMs of Corsair Vengeance DDR3 CMZ16GX3M4X1600C9 with XMP profile, 4GB each, total 16GB), with FSB up to 1600 MHz, and so on. This motherboard, as all mobos of this level, gives the user the ability for an advanced and analytical overclocking via its special menu item of Gigabyte in the BIOS, called "M.I.T. - Motherboard Intelligent Tweaker". With this, the user can see, control and adjust the following CPU parameters (I am referring only to the CPU parameters, because this advanced menu item also supports overclocking to the other subsystems of the motherboard, such as RAM memory, chipset, PCI-E slot etc., which I am going to mention later on, at the end of this topic):

- CPU Clock Ratio It is usable when the CPU clock is unlocked. However, I found out that the clock of my CPU is locked. Therefore, I will probably not be able to use this function.
- Fine CPU Clock Ratio (in combination with the above item, it allows micrometric adjustment of the clock ratio at 0.5 steps, i.e. from 8x to 8.5x)
- CPU Host Clock Control. Enables or disables the control of CPU host clock. Enabled will allow the CPU Host Frequency item below to be configurable.
- CPU Host Frequency (Mhz). Allows you to manually set the CPU host frequency. This item is configurable only if the above item is enabled. For my CPU it must be set to 400 MHz for normal operation (8 x 400 = 3200 MHz or 3.2 GHz)
- CPU Clock Drive (it allows the adjustment of CPU amplitude and of the North Bridge from 700mV up to 1000mV, with default 800mV)
- CPU Clock Skew (Allows the user to set the CPU clock prior to the North Bridge clock. Options are: 0ps~750ps. Default: 0ps)
- MCH Clock Skew (Allows the user to set the North Bridge clock prior to the CPU clock. Options are: 0ps~750ps. Default: 0ps)
- Load-Line Calibration (Enables or disables Load-Line Calibration. Enabling this feature adjusts Vdroop, keeping the CPU voltage more constant under light and heavy CPU load. Disabled sets the CPU voltage following Intel specifications. Default: Disabled. I am not sure if I know what this exactly does and if it is connected with the next 3 items)
- CPU Vcore (Default: Auto. I suppose that this item controls and adjusts the voltage of the CPU core, which, in the case of Xeon X5482, is between 0.85V and 1.35V, with standard operation at 1.2V)
- CPU Termination (Default: Auto. I don't know what this exactly does)
- CPU PLL (Default: Auto. Also, I don't know what this exactly does)
- C.I.A. 2 (CPU Intelligent Accelerator 2). It is designed to control and adjust the performance of the CPU, depending on its load and it has 5 options: Disabled-Cruise-Sports-Racing-Turbo-Full Thrust. In these options, the CPU frequency is gradually increased, depending on the option and it can reach up to 19% more.

These are the basics, which the user can use.

In order to allow the O/C experts, that read this topic, to give me a better advice, the following parameters for the other subsystems of the moterboard can also be "tweaked" via the "M.I.T" advanced menu of the above motherboard BIOS:

A. DRAM Performance Control. This menu allows tweaking of the DRAM subsystem basics, but in addition to this, there is a more analytical tweaking of the DRAM subsystem, allowing the user to adjust the timings for each DIMM and each channel separately plus several other paramemters for DRAM, which require a lot of space to be copied here. The following basic "tweakings" of DRAM can be seen in this menu:

- Performance Enhance. Allows the system to operate at three different performance levels:
-> Standard Lets the system operate at its basic performance level.
-> Turbo Lets the system operate at its good performance level. (Default)
-> Extreme Lets the system operate at its best performance level.

- Extreme Memory Profile (X.M.P.). Allows the BIOS to read the SPD data on XMP memory module(s) to enhance memory performance when enabled.
As I already wrote above, my Corsair RAM profile is of XMP Profile and it can be tweaked, according this menu.
->Disabled Disables this function. (Default).
->Profile1 Uses Profile 1 settings.
- >Profile2 Uses Profile 2 settings.
By the way, since my RAM is of XMP profile, does this mean that, when enabled, it can follow the basic BIOS settings, without being necessary to deal with separate adjustments of it?

- (G)MCH Frequency Latch. Allows you to fix the chipset frequency at system bootup. Options for adjusting memory multiplier below may differ according to the fixed frequency. Options are: Auto (default), 200MHz, 266MHz, 333MHz, 400MHz.

- System Memory Multiplier (SPD). Allows you to set the system memory multiplier. Options are dependent on CPU FSB and the (G)MCH Frequency. Latch settings. Auto sets memory multiplier according to memory SPD
data. (Default: Auto).

- Memory Frequency (Mhz). The first memory frequency value is the normal operating frequency of the memory being used; the second is the memory frequency that is automatically adjusted according to the CPU Host
Frequency (Mhz) and System Memory Multiplier settings.

- DRAM Timing Selectable (SPD). Manual allows all DRAM timing control items below to be configurable. Options are: Auto (default), Manual.

After the above first basic settings, there is one more "standard" submenu, called "Standard Timing Control". Within this, the following can be tweaked:

- CAS Latency Time
Options are: Auto (default), 4~11.
- tRCD
Options are: Auto (default), 1~15.
- tRP
Options are: Auto (default), 1~15.
- tRAS
Options are: Auto (default), 1~63.

Then, an "Advanced Timing Control" (more analytical tweaking menu) follows, which I am going to skip, because it takes a lot of space, as I wrote above. Finally, the BIOS allows "tweaking" for PCI-E Bus and DRAM Voltage control, etc.

Given all above parameters for the CPU and the other subsystems, I would like to clarify the following:

1) If I want, can I use all - especially those affecting CPU tweaking - or only some of of them? And if yes, which ones?

2) Scoping in a mild-to-moderate overclocking (i.e. from its standard 3.2 GHz to go up to 3.8 or up to 4.0 GHz), except the CPU clock adjustment, which I suppose it will alter the CPU frequency, what other item must I consider, so that the CPU clock change harmonizes with other parameter or parameters?

3) If I finally do the overclocking, will it be necessary to alter (or adapt) the other subsystems of the motherboard (i.e. RAM or PCI-E BUS), or can I leave them untouched?

Thank you in advance.

(In order to avoid unnecessary discussions, I have taken care of the CPU cooling, so that higher temperatures shall be controlled. A water cooling system shall be applied in this case, taking care of course, to control all possible dangers that water cooling may have).
-

[agent_x007]

Well, U did not do the smart thing - bought high multi CPU (x9 or more).
U choose CPU with small multiplier (ie. "x8") and because of that, U will need at least 500MHz on FSB (or 2000MHz effective), to get to 4GHz.

In case of "Harpertown" Overclocking (OC) is exacly the same as on "Penryn".
Max. Vcore (long term) is ~1,35V (with Vdroop).
U can of course go over that for benchmarks.
But I don't recommend going over it for 24/7 use.

As far as OC go :
U can increase CPU Frequency only by increasing FSB Frequency.
It works like this :
FSB Frequency (real) x CPU Multiplier = CPU Speed.

Now, altering FSB Freq. will change Memory frequency as well.
But first, U should know that there is a "lock" for PCI bus (at "33,33MHz"), and PCI-e bus (at "100MHz"), so that other components (such as HDD controler, Audio, LAN, etc.), will NOT be affected by FSB changes.

Going back to (D)RAM Frequency :
Just try to keep it as close to XMP/Default values as possible, after changing FSB Freq.
+ Better got it "underclocked", than overclocked, as the latter can cause BSOD's (random restart's, hang's, freezes, etc.) that are independent of CPU stability.

With incresing OC "%", your system may become unstable (ie. U will get BSODs/errors) at some point. When it will, there are two options :
1) U can increase Voltage, or
2) Decrease FSB Frequency.

I don't know how far U want to go in case of Voltages/Frequency, but usually U need to change only Vcore (ie. increase it), to get system stable again. Problem is that with high FSB (450MHz+) it may not be enough to got it stable. It may need "FSB Termination" and/or "CPU PLL" increase, as well as Vcore increase, to stabilize it again at new settings.
The exact point when U will need to change additional voltages depends on "silicon lottery" (how good chip U got).

Warning : U can "instant kill" a CPU, if U go too high on CPU Termination/PLL voltage.
Vcore usually shortens life span of chip, but (when temperatures are under control), it shouldn't kill CPU right away (of course, if U won't set it REALLY high, ie. 1,75V+ on air cooling ).

Good luck (I hope I didn't messed up English language too much ).

[Pan_Melas]

My, my...!

This is really the first informative reply (and advice) I get for this topic (having posted not only in this forum, but in some other similar ones, especially those of my own country & language). Thanks, very much, mate, for your time!

[Guest]

You also have to consider one more thing: the highest TDP from the list of CPUs for your motherboard is 135W and you have a 150W CPU.
Perhaps at the nominal speed of the CPU everything will be ok, but overclocking could be a problem for the motherboard.

[Pan_Melas]

[agent_x007]

U "want" 1,28V to get to 3,8-4GHz, OK.
But what U want, and what U get, aren't always the same thing

U may have a CPU that overclocks like hell, and get to 4GHz at 1,25, but also the opposite might be true, and your CPU can't be stable at 3,8GHz, even with Vcore = 1,35V.
Like U said - experimenting is nessesary.
Just keep watching Core temperatures when you change Vcore Voltages (at Load). Going too high isn't good for MB or CPU or that matter.

Yes. Manual set 100MHz in PCI-e.
As for PCI bus. If U can't see option for PCI, it is possible that it's linked to PCI-e bus (via bridge chip), so locking PCI-e locks PCI as well.

As for RAM, U assume correct
After Big FSB Freq. change, u might consider changing DRAM Freq. to ease stress on RAM modules a bit (overclocking both is no good if U don't know the limits of your parts, yet).
SPD = 1333MHz at 9.9.9.24 @ 1,5V.
SPD is for compatibility (if XMP profile can't be activated - when MB doesn't support XMP for example).
XMP = 1600MHz at CL9.9.9.24 and 1,5V DRAM Voltage.
That's best setting (performance/stability wise) for your RAM's, so keep them as close to 1600MHz as possible. FSB increase, will change only DRAM Freq. so timings and Voltage don't need to be changed.

BTW, I do not know if XMP can alter/change/block your FSB overclocking (XMP forces MB [MotherBoard] to change settings that enable XMP profile to work).
But since U change FSB Freq. in few MHz increments, XMP can't "lock" DRAM Freq. in 1600Mhz at all times. Basicly U can't "match" normal settings at all times, because memory multiplier doesn't work that way.
U can either have for example 1333MHz or 1600MHz no in-between values.
When U OC FSB, that values will change as well, so 1333 may go to 1500MHz and 1600 may change to 1700+MHz.
That's when, U may/will need to change DRAM Frequency to lower value than "normal" (ie. 1500Mhz) - to keep it stable.
1500Mhz is less than 1600MHz so a XMP profile probably won't work in this example.

As for "%" OC :
I meant that if U go 30%+ OC U will need to change something more to get system stable again. I never use "C.I.A. 2" or similar things since they are stupid (for me it's Manual OC all the way for LGA775 ).

CPU Termination = FSB Term.
CPU PLL = CPU PLL (obviously )
DRAM Termination shouldn't be change (at least not in Your case).
Keep it as it is (on AUTO).

I think that's all (for now).

PS. TDP Wattage is only a guideline, not a rule
Don't try this at home :
P5B with OC'ed PXE 840 @ 3,74GHz : LINK
So how high that TDP can be again ?