Does 790FX + SB750 = High-End Overclocking?

Foxconn A79A-S

Foxconn took a more calculated approach to launching its high-end Spider platform motherboard, waiting for the SB750 to arrive before releasing any 790FX product. That means the A79A-S is an all-new product, and that Foxconn had a very long time to prepare and test its new board, since the earlier southbridge is pin-compatible.

PCI Express 2.0 slots look somewhat more crowded than on the competing Asus product, but looks can be deceiving—both products block off one, and only one, graphics card slot when double-thick graphics coolers are used. Both motherboards are limited to a maximum of three double-slot cards, such as the high-end HD 4870 or four single-slot cards, such as the mid-market HD 4850.

Foxconn’s use of a five-phase voltage regulator might be seen as a potential weakness in light of Asus’ 10-phase design, but our overclocking results are a better indicator of the effect on stability.

Some Windows XP users will be happy to see the rarely used A79A-S floppy connector in a more advantageous location, since these ease installation of the venerable OS on RAID arrays, but the similarly outdated Ultra ATA connector is still found below the motherboard’s center line.

We have mixed feelings about the Serial ATA port orientation. Four forward-facing ports allow long graphics cards to be used without interference, but they may themselves be blocked off by lower-bay hard drive cages on some tower-style cases. The other two ports face outward, allowing installation in tight cases but with the potential to be blocked off by long graphics cards. At least Foxconn has considered both circumstances, and we doubt many users will put long cards into tight cases.

Like its competition, the A79A-S has power and reset buttons near the front of its bottom edge, which are perfect for bench testing. But Foxconn goes one step further by adding a two-digit POST code reader to aid in diagnosing failed overclock attempts (as well as other boot failures). Also notice the removable BIOS IC, a feature that makes bad-flash recovery as easy as plugging in a replacement.

Onboard Devices

Other than the addition of a second network controller, Foxconn’s A79A-S provides similar onboard features compared to the Asus M3A79-T Deluxe. Foxconn is very proud of its choice in audio codec, as the ALC888SD offers both Dolby Digital Live and DTS Connect. These competing technologies allow live multi-channel sound streams, such as gaming audio, to be encoded in real time to a single digital output.

The A79A-S has twice as many rear-panel eSATA connectors as the M3A79-T Deluxe, but neither motherboard offers an internal connection for adding front-panel eSATA to the third-party controller. Foxconn also has twice as many PS/2 and Network ports as its chief rival.

Two network controllers occupy the center portion of the A79A-S motherboard’s rear edge. A little farther up, JMicron’s tiny JMB362 eSATA controller is found forward of the rear-panel analog audio jacks.

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The ALC888SD audio codec is placed very closely to the front-panel audio header, with its shorter trace length likely to reduce headset noise. On the other hand, placing these so far from the rear panel jacks could increase speaker noise. Foxconn still claims a 95db signal-to-noise ratio.

The other problem with having the front-panel audio header in the lower rear corner is that the front-audio cables of some cases simply won’t reach. We could easily blame case manufacturers for this problem, but we’d then question why cables must be so long. We’d like to see motherboard manufacturers move this connector to a more advantageous location.