Does 790FX + SB750 = High-End Overclocking?

Overclocking Results

Most readers have seen AMD’s overclocking utility, and many have heard about huge overclocking gains made possible by using Advanced Clock Calibration (ACC) on SB750-equipped motherboards. Unfortunately, we didn’t have similar results this time.

Our first problem with AMD Overdrive is that it didn’t initially support ACC when ACPI was enabled. Meanwhile, upgrading to version 2.1.4 solved that problem.

Overdrive includes advanced features such as automatic overclocking with stability tests, but our system would lock each time it reached approximately 2.94 GHz on either motherboard. Our second problem was that the settings were lost upon restart, so the program never really finished.

Our third problem was that while ACC adjustment did appear to have some effect on overclocking capability, it wasn’t enough to get us over 3.00 GHz when using AMD Overdrive to make remaining adjustments. Our best overclocking results were achieved the old fashioned way, through BIOS voltage and clock speed controls.

With a mere 20 MHz lead over MSI’s nForce 780a SLI motherboard, the win by Foxconn’s A79A-S certainly didn’t lend any credence to the advanced capabilities of SB750-equipped motherboards. Furthermore, the SB750-equipped M3A79-T Deluxe didn’t even match the nForce 780a SLI.

Anyone worried about how the A79A-S has only “half as many” voltage regulator phases as the M3A79-T Deluxe can rest easy with the above overclocking results, as there are plenty of other more pressing limitations. We don’t know if the M3A79-T Deluxe’s voltage regulator is overkill or if the A79A-S components are simply upsized, but we can see that the board with the fewest regulator components had the best overclocking stability.

Putting aside ultimate CPU stability, we also realize that some buyers don’t have an unlocked “Black Edition” Phenom and must instead overclock using the HT base clock. It’s often possible for such systems to run out of HT overclocking capability long before the processor reaches its limit, so we tested each motherboard to find out how far its HT clock could be pushed starting at the 1,200 MHz data rate and increasing the base clock incrementally.

Phenom users who would otherwise be significantly limited by a relatively low-core multiplier will find excellent results with the Asus M3A79-T Deluxe.

One of the more exciting performance features of Phenom processors is support for DDR2-1066 memory, yet using the highest memory ratio can again limit how far the HT base clock can be pushed. Due to the popularity of 4 GB configurations, we used 2 GB modules for this test.

Foxconn’s A79A-S has slightly better memory overclocking stability with two modules installed, while the Asus M3A79-T Deluxe isn’t bogged down as much by four. MSI’s 780a SLI motherboard isn’t far behind either 790FX + SB750 sample.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.
  • afrobacon
    very nice review
  • neiroatopelcc
    "Also notice the removable BIOS IC, a feature that makes bad-flash recovery as easy as plugging in a replacement."
    I don't know about you guys, but I haven't had a flash going wrong since a P2B board from the stoneage
  • cangelini
    neiroatopelcc"Also notice the removable BIOS IC, a feature that makes bad-flash recovery as easy as plugging in a replacement."I don't know about you guys, but I haven't had a flash going wrong since a P2B board from the stoneage
    Call it paranoia from a guy who changes BIOSs on an almost daily-basis on one board or another (me, not Thomas, though he does his fair share of updating, too).
  • neiroatopelcc
    Perhaps it's just the luxury of gigabyte's dual bios that makes me not care for removable ic's but I just don't see the relevance. Nobody has an eprom writer for those chips at home anyway, and with prices of many motherboards closing in on what a new chip would cost it's only truely useful for the expensive boards - and if an amd board is expensive, then it's targetted at the wrong people.
  • slomo4sho
    Thanks for the review. As you have stated, only way that AMD can compete with INTEL is to provide better clock speeds on their chips. Intel has shot forward with giant improvements and AMD has been stuck on the side lines. Their 45nm chips are still not on the market and Intel is already making moves to switch to 32nm.

    Sadly, this is going to be tough hill to climb for AMD to become competitive again. I wish them luck though, the consumer is always the winner when corporations compete :)
  • Tropoc
    Im sorry, but this is rubbish:

    Ive got a phenom x4 9950 placed on a ASUS m3a32 mvp deluxe motherboard.

    With stock voltage and stock cooling ive cranked it up to 3.2ghz and it runs perfectly stable. (this was done by only adjusting the multiplier)

    A friend of mine have the same setup as me but an aftermarket cooler (noctua nh-u12p) and hes overclocked it up to 3.4ghz, again running stable.

    On Overclocking forums i read about people cranking this CPU up to 3.6ghz on air (noctua nh-u12p) without any wizardry.

    This test is flawed and im very dissapointed about tomshardware and what i feel is an effortless test of this setup.

    Im an Intel guy myself but at least im honest about intels oponents, and in this case the review should end up with AMD being amazing value for money and that the future is a bit (not alot) brighter for AMD.
  • slomo4sho
    You realize that the Q6600 can also be overclocked to 3.6GHz on air as well without much difficulty? Both processors are at the same price point. The only difference is that the 9950 is AMD's top end chip and the Q6600 is a entry level quad core from Intel...

  • Tropoc
    im aware of that yes, but the problem here is tomshardware not the q6600... why? they didnt get it over 3.12ghz, which frankly is pathetic.

    and the 9950 is cheaper then the q6600 its cheaper then about every intel processor out there (even the dual cores such as e8400 etc).

    Im not saying it is a better processor then what intel has lined up, what im saying is that it is amazing value for money. and much better at overclocking then tomshardware managed to get out of it thats all :D
  • marzzes
    Oh my God, you guys went with a Jetway over a DFI board! Not to mention just one vidio card and a mid range one at that, how about two 4870X2’s??.. I mean isn’t that what we buy these boards for?…….Oh and what kind of memory each board can handle or why didn’t you go with a Thermalright cpu cooler, hell if your going to oc water cooling is the way to go!
    Obviously Tom wasn’t interested in doing this review!……..
  • geckoar
    I got my 9950 running at 2.85 ghz so thir numbers are not too bad. Im running it on a 790FX+SB600 K9A2 mobo. I could go more but my DDR2 800 RAm is holdinmg me back... I guess I should have gotten DDR2 1066 RAM.
    But I game at 1080P res. wiht a 4870 and I get over 30FPS in most of my games At max setting.

    Good Review.