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TekSpek Motherboards
NVIDIA nForce 5

NVIDIA nForce 5

Date issued:


This TekSpek explains what's new and improved about NVIDIA nForce5 core logic.

The Technology

The recent release of AMD's new unifying processor socket, Socket AM2, gave NVIDIA the chance to release new core logic to go with it, allowing its board vendor partners to implement new designs that carry the socket and DDR2 memory support.

Called nForce5, it bests nForce4 in a number of ways in terms of base features, and those offered by the flagship nForce5 590 SLI when compared to the old nForce4 SLI X16. This TekSpek seeks to explain the differences in terms of what's new and improved on NVIDIA's brand new core logic for Socket AM2.

We'll stick to the high-end enthusiast class variation of nForce5 -- nForce5 590 SLI -- for the time being, since it bundles all the nForce5 features and performance enhancements. There's also nForce5 570 SLI, 570 Ultra and 550 which we'll cover nearer the end.

Like the AMD version of nForce4 SLI X16 before it, nForce5 590 SLI is a two-chip core logic set based on PCI Express and supporting NVIDIA SLI. The C51XE 'northbridge' IC connects to the CPU and provides the PCI Express interconnect for the first graphics board, and the MCP55 'southbridge' does the rest, including implementing another 28 lanes of PCI Express. 570 and 550 variants just implement MCP55 and thus are single chip.

The pair of ICs further supply a new 6 port SATA2 controller with RAID, 10 USB 2.0 ports, HD Audio link for use with a HD Audio CODEC, new and improved ActiveArmor networking controller with dual GigE MACs and new features, SLI Memory/EPP, LinkBoost overclocking technology and more.

It's not often you get to add factory overclocking to the list of core logic features a vendor supports across all of its board partners, but nForce5 590 SLI allows your author to do just that. NVIDIA screen the ICs used to make nForce5 sets and use the best for 590 SLI.

Let's talk about each feature in turn, including the factory clock adjust.


LinkBoost™ is where all the overclocking happens, an NVIDIA nForce5 590 SLI board upping the clocks well past reference to increase performance. Effectively all the major links get a 25% clock boost with LinkBoost™ enabled, including the CPU's HyperTransport<->C51XE link (itself 16-bit both ways), the PCI Express lanes driving the graphics hardware, and also the HyperTransport link between C51XE and MCP55.

The PCI Express graphics link overclocking seemingly only happens with 7900 GTX for the time being, NVIDIA quietly locking it out from use with other 90nm G71-based SKUs like 7900 GT.

The important thing is that it's supported by NVIDIA, doesn't void any warranty and is guaranteed to work. It's been found that 7900 GTX overclocks best when the PCIe link its sitting on is driven higher (possibly some internal clock is driven by the PCIe reference clock), so the LinkBoost™ jump might enable even higher user-led graphics overclocks via the BIOS or software.

nForce5 590 SLI also defines a set of voltage ranges for system components that can be altered in real-time by software and the BIOS, in order to make LinkBoost™ work properly, should a voltage increase be needed to sustain the new clock level. That leads on nicely to SLI Memory.

SLI Memory

We list SLI Memory as a CPU feature, given the nature of the on-board memory controller.

EPP/SLI Memory exists to factory overclock your memory modules if they have support, on nForce5 590 SLI. The basic premise of EPP is that it hijacks part of the established SPD ROM area on memory modules in order to provide more comprehensive timing and voltage information to the core logic, which uses that information to set the best parameters on the CPU's memory controller.

It largely takes the hard work out of an overclock a user would most likely attempt themselves, running your memory modules at higher speeds (with the right timings and voltage) without the worry about stability.

However, it requires the support in the memory module for a correctly programmed EPP memory space inside the SPD ROM. Look out for the "SLI Ready" sticker and specification when you buy your module packs, and of course since it's a Socket AM2 core logic set it just applies to DDR2 memories. Want to see a pack of SLI Ready memory? Of course you do.

Note the SLI Ready sticker. That particular Corsair XMS2 8500 DDR2 is rated to DDR2-1066 and in an SLI Memory nForce5 590 SLI system it'll be run at around that speed, despite the memory controller on Athlon 64 FX and Athlon 64 X2 only officially supporting DDR2-800. That's what SLI Memory is all about, really.

It requires BIOS support on the nForce5 590 SLI board and the right memory modules, which then enable an SLI Memory on/off toggle in the board BIOS that you can set for faster memory speeds.

Each module supplies at least 2 EPP profiles for the nForce5 590 SLI set to program the memory controller with, with modules possibly supporting 4 abbreviated profiles should the vendor choose to provide them.

It's not the first time a chipset has allowed overclocking past the official norm, indeed far from it, but it's definitely the first time it's been enabled with the help of the memory vendors to make it easy and warrantied. Even if no other core logic vendor chooses to support it, and even if JEDEC reject it when presented with the spec, EPP modules work just fine in non nForce5 mainboards, so you can't lose out by buying the modules.


ActiveArmor has come under considerable fire since its launch with nForce4 over a year ago. Promising hardware offload and acceleration of various bits of the TCP/IP networking stack and its integrated firewall under Windows, ActiveArmor hasn't always worked as promised, NVIDIA increasingly disabling bits of the hardware offload in driver revisions after demonstratable data corruption of network transfers and performance problems..

So back to the drawing board was the best option for nForce5, since NVIDIA see significant merit in hardware assist in networking by their core logic.

NVIDIA say they've got it right with nForce5, fixing the issues with hardware assist while further increasing the feature set for nForce5 590 SLI (and other nForce5 variants). The backbone of that is the simple provision of a pair of gigabit Ethernet controllers on the MCP55 IC, each with support for all the new networking features and support for full-duplex 1Gib/sec transfers. Let's cover the features covered by faintly silly marketing names.


FirstPacket is what NVIDIA like to call their hardware acceleration of quality-of-service (QoS) in nForce5. Your author isn't 100% sure if it's acceleration of a defined QoS spec like IEEE 802.1Q, or not, but what it does it let traffic from defined applications on your system transmit and receive at a higher priority level than other network traffic.


NVIDIA give you two network controllers in nForce5 590 SLI, right? But you only use one like most folks, right? Why not get the networking controllers to party together and provide a double-wide connection to whatever network it is you connect to?

Simply put, if you've got a spare port on your switch or router, plug both ports on your 590 SLI board in and let it appear to Windows as a single interface. Should you pull one cable out or otherwise lose one of the links, it autonegotiates a new link with just one cable and carries on working with no downtime or loss of data.

It's not a new concept, indeed we vaguely remember ATI mentioning that their core logic can do something very similar, but it does provide a bit more bandwidth if you can make use of it on the network you're connected to.

Disk Controller

NVIDIA give their disk controller an upgrade in nForce5 590 SLI, too. Where once there were four SATA2 ports on nForce4, there are now six on nForce5 590 SLI. You can RAID5 a pair of three disk arrays for hardware accelerated big disk collections (as well as RAID0, 1 and 0+1 across the lot) and the controller also contains specific tuning for command queuing on various disks and their firmwares.

Got a drive on the (as yet unpublished) list that nForce5's SATA controller knows and loves? It'll do the command queuing a bit better than it might have before, giving you better performance on heavy random access loads to your disks.

NVIDIA also claim support for nForce5 RAID volumes during the install and boot process of Microsoft Windows Vista (whenever that gets released), without having to supply the installer any extra driver disks.

nForce5 590 SLI Summary

If you decide that high-end AM2 is where you want to plant your PC flag, nForce5 590 SLI seems a mighty fine place to do it on paper. Performance and features are laid out before the user, and there's very little a well sorted 590 SLI board shouldn't do in the pursuit of high-end computing nirvana.

nForce5 570 SLI, 570 and 550

Using 590 SLI as a base, 570 SLI basically removes the C51XE and moves to 8+8 SLI as a consequence, using a single chip. LinkBoost disappears too, but that's it.

570 then removes SLI support, and 550 further removes FirstPacket, 2 of the 6 SATA ports and RAID5 support, creating the lowest cost version of the core logic. Physically, all share the same silicon, just NVIDIA productise using features.


And that, as they say, is that. Four variants, with 590 SLI being the core logic for AMD Socket AM2 right now and 570 and 550 holding up the budget end of the market. If you're into AMD just now and their DDR2 platform appeals, NVIDIA nForce5 590 SLI is where its at. Hope this somewhat lengthy explanation helped you understand why!