E7500 Chipset

Iwao Makino rickey-co at mug.biglobe.ne.jp
Fri Jul 19 05:25:44 PDT 2002

If you want to get
Good memory bandwidth, perhaps i860 chipset base is good idea, but be careful,
if you want to get
PCI bus performance from them, DON'T USE i860 based board.

Here's good reason:

Maurice said while ago(and others too, few times)
If you want to see a REAL bug, and one that both severely cripples 
performance and is NOT fixable, look at this "errata" in the Intel 860 
chipset ( the chipset for dual XEON P4 motherboards):

In the file found at:

Intel lists errata for the 860 chipset.
One of these states:

"5. Sustained PCI Bandwidth Problem:
  During a memory read multiple operation, a PCI master will read more than 
one complete cache line from memory. In this situation, the MCHpre-fetches 
information from memory to provide
optimal performance. However, the MCH cannot provide information to the PCI 
master fast enough. Therefore, the ICH2 terminates the read cycle early to 
free up the PCI bus for other PCI
masters to claim.

Implication: The early termination limits the maximum bandwidth to ~90 MB/s.

Workaround: None

Status: Intel has no fix planned for this erratum."

This effectively limits the bandwidth of the PCI bus to 90MB per second.
Considering this is a chipset designed for servers, and is equipped with 
PCIslots at 64 bit, and 66MHz, it  should have a bandwidth of over 
If you buy one of these, and spend money on high performance SCSI, gigabit, 
or other devices, you are wasting your $$.
At 9:48 -0400 18.07.2002, Neil McFadyen wrote:

>Any comments on the 860 chipset, for example the supermicro P4DCE+

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