Tag Archives: ECC

CPU L2 Cache ECC Checking from The Tech ARP BIOS Guide

CPU L2 Cache ECC Checking

Common Options : Enabled, Disabled

 

Quick Review of CPU L2 Cache ECC Checking

The CPU L2 Cache ECC Checking BIOS feature enables or disables the L2 (Level 2 or Secondary) cache’s ECC (Error Checking and Correction) capability, if available.

Enabling this feature is recommended because it will detect and correct single-bit errors in data stored in the L2 cache. As most data reads are satisfied by the L2 cache, the L2 cache’s ECC function should catch and correct almost all single-bit errors in the memory subsystem.

It will also detect double-bit errors although it cannot correct them. But this isn’t such a big deal since double-bit errors are extremely rare. For all practical purposes, the ECC check should be able to catch virtually all data errors. This is especially useful at overclocked speeds when errors are most likely to creep in.

So, for most intents and purposes, I recommend that you enable this feature for greater system stability and reliability.

Please note that the presence of this feature in the BIOS does not necessarily mean that your processor’s L2 cache actually supports ECC checking. Many processors do not ship with ECC-capable L2 cache. In such cases, you can still enable this feature in the BIOS, but it will have no effect.

 

Details of CPU L2 Cache ECC Checking

The CPU L2 Cache ECC Checking BIOS feature enables or disables the L2 (Level 2 or Secondary) cache’s ECC (Error Checking and Correction) capability, if available.

Enabling this feature is recommended because it will detect and correct single-bit errors in data stored in the L2 cache. As most data reads are satisfied by the L2 cache, the L2 cache’s ECC function should catch and correct almost all single-bit errors in the memory subsystem.

It will also detect double-bit errors although it cannot correct them. But this isn’t such a big deal since double-bit errors are extremely rare. For all practical purposes, the ECC check should be able to catch virtually all data errors. This is especially useful at overclocked speeds when errors are most likely to creep in.

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There are those who advocate disabling ECC checking because it reduces performance. True, ECC checking doesn’t come free. You can expect some performance degradation with ECC checking enabled. However, unlike ECC checking of DRAM modules, the performance degradation associated with L2 cache ECC checking is comparatively small.

Balance that against the increased stability and reliability achieved via L2 cache ECC checking and the minimal reduction in performance seems rather cheap, doesn’t it? Of course, if you don’t do any serious work with your system and want a little speed boost for your games, disable CPU L2 Cache ECC Checking by all means.

But if you are overclocking your processor, ECC checking may enable you to overclock higher than was originally possible. This is because any single-bit errors that occur as a result of overclocking will be corrected by the L2 cache’s ECC function. So, for most intents and purposes, I recommend that you enable this feature for greater system stability and reliability.

Please note that the presence of this feature in the BIOS does not necessarily mean that your processor’s L2 cache actually supports ECC checking. Many processors do not ship with ECC-capable L2 cache. In such cases, you can still enable this feature in the BIOS, but it will have no effect.

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Chipkill – The BIOS Optimization Guide

Chipkill

Common Options : Enabled, Disabled

 

Quick Review

Chipkill is an enhanced ECC (Error Checking and Correcting) technology developed by IBM. Like standard ECC, it can only be enabled if your system has two active ECC memory channels.

This BIOS feature controls the memory controller’s Chipkill functionality.

When enabled, the memory controller will use Chipkill to detect single-symbol and double-symbol errors, and correct single-symbol errors.

When disabled, the memory controller will not use Chipkill. Instead, it will perform standard ECC to detect single-bit and double-bit errors, and correct single-bit errors.

If you already spent so much money buying ECC memory and a motherboard that supports Chipkill, you should definitely enable this BIOS feature, because it offers a much greater level of data integrity than standard ECC.

You should only disable this BIOS feature if your system only uses a single ECC module.

 

Details

Chipkill is an enhanced ECC (Error Checking and Correcting) technology developed by IBM. Like standard ECC, it can only be enabled if your system has two active ECC memory channels.

Normal ECC technology make use of eight ECC bits for every 64-bits of data and the Hamming code. This allows it to detect all single-bit and double-bit errors, but correct only single bit errors.

IBM’s Chipkill technology makes use of the BCH (Bose, Ray-Chaudhuri, Hocquenghem) code with sixteen ECC bits for every 128-bits of data. It can detect all single-symbol and double-symbol errors, but correct only single-symbol errors.

A symbol, by the way, is a group of 4-bits. A single symbol error is any error combination within that symbol. That means a single symbol error can consist of anything from one to four corrupted bits. Chipkill is therefore capable of detecting and correcting more errors than standard ECC.

Unlike standard ECC, Chipkill can only be used in systems with two channels of ECC memory (128-bits data width configuration). This is because it requires sixteen ECC bits, which can only be obtained using two ECC memory modules. However, it won’t work if you place both ECC modules in the same memory channel. Both memory channels must be active for Chipkill to work.

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This BIOS feature controls the memory controller’s Chipkill functionality.

When enabled, the memory controller will use Chipkill to detect single-symbol and double-symbol errors, and correct single-symbol errors.

When disabled, the memory controller will not use Chipkill. Instead, it will perform standard ECC to detect single-bit and double-bit errors, and correct single-bit errors.

If you already spent so much money buying ECC memory and a motherboard that supports Chipkill, you should definitely enable this BIOS feature, because it offers a much greater level of data integrity than standard ECC.

You should only disable this BIOS feature if your system only uses a single ECC module.

 

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