Overclocking & Final Words

As a general use CPU for office applications and your normal day-to-day tasks, the Sempron is quite strong and definitely faster than its Celeron D counterpart. However, applications for the power user, workstation user or the gamer suffer greatly because of its single channel memory controller and small L2 cache. But given that the new Sempron is built on AMD's cooler 90nm process, we decided to see how far the new chip would overclock.

The Sempron 3300+ has a default core voltage of 1.400V. Bumping it to 1.500V and increasing the FSB to 240MHz yielded us a nice and even 2.4GHz, a 20% increase in clock frequency. But the real question is, how much of a performance boost will the added clock speed bring you?

While we didn't run a full suite of tests, we picked a handful of our benchmarks on which to focus in order to get a good idea of whether or not overclocking will make Sempron any more desirable. The end result was basically this:

  • In applications where the Sempron was already quite competitive with similarly clocked Athlon 64s, the overclocked Sempron did extremely well, as you would expect.
  • In those applications, particularly games, where the Sempron didn't do so well, overclocking did nothing to help. For example, despite a 20% increase in clock speed, Doom 3 performance only went up by around 4% when we overclocked the Sempron 3300+.

Our overclocking findings helped create a general recommendation for the Sempron; for those users who are most likely to want to overclock to increase performance, the Sempron (despite its wonderful overclockability) isn't the chip for you. Gamers will find that similarly priced Athlon 64s are much better performers, especially if you are able to use the Socket-939 platform.

If you're debating between a Sempron 3100+ and a 3300+, the two often times perform identically to one another. Some applications will favor the Sempron 3100+'s larger L2 cache, while others will favor the higher clock speed of the 3300+. We generally prefer the 3300+, thanks to its cooler running 90nm process, but the two do perform very similarly and are hard to tell apart in real world usage.

Compared to Intel's Celeron D, the Sempron continues to be the better buy and overall, the better performer. According to Intel's roadmaps, a 3.2GHz Celeron D is due out soon, but until then, the Sempron manages to hang on to the budget CPU throne.

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  • coldpower27 - Monday, April 18, 2005 - link

    Maybe this is a way for AMD to get rid of "sucky" Venices. Though at 127US pricing, it's value is questionable over getting the Athlon 64 2800+.
  • Illissius - Monday, April 18, 2005 - link

    s/half the memory controllers/half the channels of memory/
  • Illissius - Monday, April 18, 2005 - link

    Are we looking at the same graphs? There were quite a lot where the 3300+ significantly outperformed the 3100+ (granted, also a few where they were identical, but very few where the 3100+ was faster).
    Which begs the question: wtf has AMD done to these things' memory controller? In many tests it ran dead even with or even outperformed the A64 3200+, with half the memory controllers and a fourth the cache (note: no, I didn't miss eg. the gaming benches where it rather sucked, but it's very surprising for it to give that kind of performance *anywhere*). At the same time, from every benchmark I've seen, Venices (Venii? :D) are only very slightly faster than Newcastles/Winchesters... strange.
  • paulsiu - Monday, April 18, 2005 - link

    With a reduce cache, the 3300 did not seemed like a good deal especially if it barely beats the 3100. Why not just get a 3100 or overclock it. Better yet, get a A64 2800+.

    Once you hit a Sempron 3100+, their value becomes highly questionable because an A64 only cost a little bit more. The problem is that AMD appears to be discontinueing all A64 for the 754 socket with the exception of mobile A64. Few Mb manufacturer support mobiles directly.

  • AtaStrumf - Monday, April 18, 2005 - link

    AT only got 2,4 GHz with increased voltage, XBIT Labs only got 2,3 GHz; damn these are some bad 90 nm chips. WTF is AMD up to? Venice chips did 2,7 GHz easy.

    As soon as get my hand on some $$$ I'm switching to S939, PCIe and a nice Venice chip. With dual core desktop Hammers not likely to appear before 2006, this will be the only game in town for the remainder of 2005 That is of course unless Pentium D tickles your fancy.

    As for X800XT distorting the gaming value CPU picture, I think this is something worth thinking about. Maybe you should include a test with a 6600GT, just to see if a more expensive CPU, coupled with a value graphics card actually makes any difference.
  • Anand Lal Shimpi - Monday, April 18, 2005 - link

    The 2.4GHz overclock was the most reasonable air-cooled overclock we could obtain. Regardless of how hard we tried, 2.50GHz was not possible with our chip.

    Take care,
    Anand
  • Calin - Monday, April 18, 2005 - link

    One big disadvantage of the Socket 754 Sempron would be the reduced memory bandwidth for an hypothetical "onboard video" solution. This is the main reason why I would like a dual channel Sempron that would cost much less than an Athlon 64. For now Sempron on Socket 754 (even with the lower price of the mainboards) is not a good choice in many regards
  • overclockingoodness - Monday, April 18, 2005 - link

    #14: Do you think AnandTech really have time for max overclocking experiements with phase cooling and stock cooling? It's all a waste. Besides, even though AT is an enthusiast site, they have more than enough projects to tackle than some enthuisiast sites who keep posting their maximum overclocks on the net. There are far too many forums and sites for that.

    And yeah, enough with the conspiracy theories. It is starting to become a regular thing in comments section of every article. People always find a way to doubt AT.

    #13: I disagree. Imagine if they used 6600GT for the CPUs and almost all CPUs scored identical. This would mean that the GPU is the bottleneck. AT's goal is to remove the potential bottleneck. I am sure some people would come in and whine about the incorrect results due to GPU limitations. Although you will not get the same performance as AT did, at least it shows the product's strenghts/weeknesses. :)
  • knitecrow - Monday, April 18, 2005 - link

    Considering the price of an sempron 3100+ to be $113 @ newegg and the price of a athlon64 2800+ to be $120; I see absolutely no reason to get a sempron!!!!!!!!!!!

  • Visual - Monday, April 18, 2005 - link

    wooo, bobsmith1492, that's the one!
    and its on top of the news section too... how didn't i notice it... i must be going nuts.

    well sorry about that.

    THEY SPY ON US WITH RAY! Wait, I must have my tinfoil hat here somewhere....

    P.S. and yeah, it'd be good to see the actual overclock max of the chip, with a mem divider and lowered htt multi and all. at various voltages. with stock and phase-change cooling. :p

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