Product: AMD 790GX Chipset
Company: AMD
Authour: Alex 'AlexV' Voicu
Editor: Charles 'Lupine' Oliver
Date: November 13th, 2008
Watching paint dry...

... is just as engaging as reviewing motherboards! This isn't because the chipset guys are less talented, nor is it because the motherboard isn't an important part of any system ... no, it's because motherboards work as intended with annoying frequency. No magic driver updates that bring X extra FPS in popular game Y, no amusing PR battles being fought around them. They simply work and ceased being a primary determinant of performance long ago. The delta in performance between an entry level motherboard and the latest and greatest uber-enthusiast proposition is rather insignificant, all else being equal.

Of course, there are reasons for which expensive boards aren't cheap (although there is none for which the prior phrase is dumb, it just came out that way): better power delivery circuitry, more PCB layers, more BIOS options, more this, more that. Whether or not the above enchilada is relevant to the vast majority of users is debatable. All in all, the take-home note is that motherboard reviews aren't all that sexy ... unless something is actually broken, making one of the competitors stands due to its insufficiencies. Did we get lucky, or was it all just a drag? Read on to find out!

The 790GX

What we have here is AMD latest greatest chipset, oh joy! Wait ... scratch the "greatest" moniker; it's not quite that. The 790GX is AMD's latest value segment offering - this means aggressive pricing, adequate features and an IGP (Integrated Graphics Processor) as the value oriented customer may not want to spend extra for a discrete graphics card that might be underutilized in his HTPC/work system. Oh, and you want it to work without much hassle, because having your HTPC crash right in the middle of that really awesome movie, or be a pain to set up in the first place, is a sure way of alienating a large chunk of your potential customer base. All of the above have been thrown into the mix, with a slight addition of extra spices, as you'll soon see, but let's not be hasty and get ahead of ourselves - let's check out the newcomer:

Starting at the top, we're greeted by:

  • AM2+ Socket: Home is where the heart is, and this is where  your new K10 (Phenom and derivatives), or your older K8 (Athlon etc AM2 CPUs work just fine) processor will reside; Deneb, the upcoming 45nm K10 refresh should also be supported, albeit a BIOS update may be required.

  • 790GX Northbridge: Fabbed on TSMC's 55nm process, it has an interesting bag of tricks attached: 22 PCI-E 2.0 lanes, 16 of them dedicated to the 2 PCI-E X16 (physical, X8 electrical if both are populated) slots, an HD3300 IGP with VGA/DVI/HDMI connectivity included, as well as an optional chunk of dedicated RAM (the performance cache bit AKA sideport memory); it communicates with the CPU via a 5.2 GT/s HT3 link (hypothetical, that assumes full 2.6GHz HT frequency, which isn't supported by any AMD CPU currently available), whilst for southbridge connectivity a 4X PCI-E 1.0 link is employed.

  • 750 Southbridge: Traditionally ATI (which means AMD nowadays) southbridges have ranged from truly awful to pretty bad - the latest attempt, the SB600, was in the "pretty bad" category, with flaky AHCI support, limited SATA/USB connectivity compared to the competition and a penchant for causing the dreaded "A clock interrupt was not received on a secondary processor within an allocated time" crash, which plagued quite a few. The new 750 southbridge attempts to break that mold.

Now, that we have an idea of how the topology of a 790GX motherboard looks, it's time to focus on the two really intriguing things that it brings: the HD3300 IGP and its sideport, and the SB750 with its mysterious and supposedly magical Advanced Clock Calibration.

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