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Posted: June 23rd, 2003
Written by: Adam Honek

The new i875P chipset

Throughout the Pentium 4ís lifespan there have been a number of chipsets forming the platform on which these processors would be used. Back in November 2002 upon the Netburt architecture launch revealed only one chipset (the i850, later revised to i850E) supporting Rambus memory. Looking back in time it was a good option mainly due to the bandwidth it could afford, something the Pentium 4 processor has always appreciated enormously. This did however have it drawbacks and the feasible alternative was to make the move to a DDR memory interface. Casting our minds back to early 2002 would remind us how Intel made this shift with the introduction of its i845D chipset family, soon to be expanded with various models with or without graphics all based on this same design. As fortunate as this was lowering cost thus bringing Pentium 4 systems to the masses there was still one aspect that needed some attention, performance. The Pentium 4ís bus has been forever running at 400, 533, and now 800MHz having the eagerness to grasp anywhere from 3.2GB/sec to 6.4GB/sec worth of data. Meanwhile only Rambus could keep up with this rich desire whereas DDR was restricted to providing at most 2.7GB/sec of bandwidth (PC2700, 333MHz memory). It has long been the reigns that Rambus equipped Pentium 4 computers excel the most speed whereas DDR systems were that modest fragment behind. Last year Intel made this an item of the past albeit at a price. The E7205 workstation class chipset delivered dual channel DDR memory synchronously operating with the CPUís FSB to match both bandwidths hand in hand.

Intelís new i875P chipset builds on what could be identified as its predecessor (E7205) though bringing to the forefront more than just a new revision or modest new features. Marketed as a high end personal computer/entry level workstation solution it holds many characteristics you would expect to see on a product falling into this segment. Matching the supported 800MHz FSB is a fully capable memory interface able to transport the bandwidth dual PC3200 DDR RAM has to offer, this ideally matching the FSB bandwidth of 6.4GB/second. Feeding such high quantities of data to the CPU will largely benefit in memory intensive operations, as we can recall this is the main reason why Rambus chipsets could outstrip DDR implementations in the past. Sadly it seems Intel decided to remove 400MHz FSB support thus leaving only 533/800MHz capability present, while this could be argued as a drawback one does soon come to realize how little if at all a 400MHz FSB CPU would benefit already having its enthusiasm fulfilled by single channel PC3200 DDR RAM. A new aspect to seize oneís attention is PAT or what Intel calls Performance Acceleration Technology. At ultra fast system speeds we experience today every cycle has its value resulting in the potential to further optimum the machineís performance. PAT is a technology only to exist in the i875P chipset endeavouring to boost memory access efficiency that one step further than on prior implementations (including the i865 family). Its essence resides in lowering timings improving upon requesting memory and then also selecting its base address consequently saving total two cycles. This is indeed good to hear and even better to own nevertheless does come across as marketing hype of what is already a standard (not forgetting positive) quality of the chipset. Such news has even been confirmed by Intel themselves, calling on PAT representing no other than a name for selecting better performing silicon during the production process of the chipset. The Northbridge consists of yet an additional value added region this time addressing a weakness of the PCI bus in the sense of networking. We discuss CSA in much more detail further on within this review. On the graphics side AGP8x rounds off the Northbridge feature list equipping 2.1GB/second to AGP 3.0 compliant graphics cards or less being furthermore backwards compatible should the device only support AGP4x.

As has long been the tradition for chipset releases they come in two branches, this is the Northbridge (as discussed above) and Southbridge that we shall discuss next. Serial ATA has since late 2001 been the anticipated successor to Parallel ATA which despite its old roots has been and still remains widely in common use today. The primary reckoning rested in the lack of integrated support meaning for using Serial ATA one had to venture out to purchase a PCI card with this facility built on. This was never an ideal solution and was largely responsible for holding Serial ATA hard drive sales from snatching market share. Intelís new ICH5/R (as oppose to the also available ICH5 option) Southbridge now supports two SATA 150 ports as part of the package finally directing the way to increased adaptation of SATA (letting old Parallel ATA die a slow graceful death) and giving a signal to other chipset manufactures to support this trend onwards. This is by far a big welcome as discarding of old technologies in favour of new for innovation is never a bad fixation. The somewhat amusing news is that floppy disk support is still very much part of Intelís latest chipset, something that must still please Sony today having introduced it back in 1981. Fortunately it is quite certain to be dropped on future platforms, or as soon as old equipped offices dispose of this computerized variant of the dinosaur.

Demanding users have in recent years approached IDE RAID as a point of interest to growing system I/O performance. Until now this has meant the utilization of other silicon chips be it integrated on motherboards or add-on cards. Prior in this review we stated how Intel now includes native Serial ATA support in their ICH5/R Southbridge but what is even more favourable is taking this a step further to in addition feature RAID capability. Stripping or mirroring (RAID 0 and RAID 1) now becomes standard opening the way to making the most out of Serial ATAís current 150MB/sec throughput limit. On the negative side there is no RAID option for onboard 4 channel Parallel ATA but as this is a dying technology it would gradually mean less and less over the coming year. The one foremost gripe surrounding Intelís Serial ATAís implementation is the two port limitation restricting to a dual SATA drive only system, unless of course aid is provided by 3rd party controllers. USB2 (480Mbits/sec) has now beyond doubt established itself as the primary interface for connecting external peripherals and for this one can never have too few ports. The i875P supports a healthy eight of these, a number set to satisfy most if not all users. The bad comes in the type of no resident Firewire (400Mbits/sec) or otherwise named 1394a capability, an interface still favoured by video capture cards for its lower latency than USB2. Integrated sound cards have developed into an almost inseparable part of modern chipsets with what better way than to round off a productís specification. The in housed AC í97 controller extends 5.1 Dolby Digital 5.1 surround sound, this secures sound capability as has been the case in previous Intel chipsets. Despite not being used by all consumers it is bound to interest OEMís seeking to save cost but not bound a systemís magnetism.


Next Page: The new i865 chipsets

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