With a good overclocking Pentium 4 2.4C, you can crank your bus up to 250 (1000 FSB) and enjoy 3.0GHz performance with the entry level Northwood. The manufacturers of enthusiast memory noticed what was going on and quickly filled the void with DDR500 memory. Until recently, DDR533 was the fastest memory you could buy, but now Corsair and OCZ have introduced PC4400, which can run at a heady DDR550.

You would be right to ask at what price you get DDR550 performance, because Corsair and OCZ both specify a very limited group of motherboards that can support this speed. Both list the Asus P4C800-E and Deluxe as compatible, and OCZ adds the DFI LAN Party 875B. That's it - only two recommended compatible motherboards for the fastest memory speed that you can buy. In addition, both specify timings as 3-4-4-8, which means speed is achieved with slower memory timings.

So, the question is, do the two new PC4400 memories meet their specifications and actually perform at DDR550? Are the trade-offs worth it? Is DDR550 a product that actually brings additional performance to the table, or are they just check list products to persuade the consumer the company markets the fastest memory that you can buy?

Why Would Anyone Want DDR550?
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  • klah - Saturday, August 14, 2004 - link

    good article
  • Pumpkinierre - Friday, February 20, 2004 - link

    #9 Perhaps you're right but all the reviews I read on the IC7 associated the game accelerator with PAT eg


    the speed increase is of the same order as PAT ie 2-5% eg:


    But I acknowledge I made an assumption so could be wrong.

    #11 I get a ~1% increase in performance on 3Dmark2001 and 3dmark2003 (default settings benchmark and catalyst 9800pro drivers) when runnung P42.6c@3.2 at mem. 5:4 2237 (OCZ 2x256Mb PC3200 platinum original SS) Game Accel.-auto. compared to 2.8 1:1 mem. oçlocked 2237@216MHz GA-F1(memory wont handle Street Racer). In general game play, the 1:1 feels smoother in my opinion.
  • TrogdorJW - Friday, February 20, 2004 - link

    "Let me tell you , it does make a speed difference. Everything benches 1-3% higher."

    So it's a measurable difference, but not noticeable. :p

    I'd still like to see real benchmarks on a variety of applications rather than just take someone's unsubstantiated claim that 3.2 or 3.4 GHz with PAT is best. With the system bus OC that you get, I don't think buying a 3.2 would be faster than buying even a 2.8C and OC'ing to 3.2. However, I have neither so I have no way of knowing.
  • retrospooty - Friday, February 20, 2004 - link

    BTW , on my Epox 4pc3a+ I can enable, or disable PAT at any speed or ram ratio.

    Let me tell you , it does make a speed difference. Everything benches 1-3% higher
  • retrospooty - Friday, February 20, 2004 - link

    PAT works on i875 fulltime... Even at 5:4

    Those settings you are referrring to " F1 or street racer" are not actually PAT , that is GAT, its just Abit's memory tweaks. On the I865 Abit boards, GAT can enable PAT (much to Intels displeasure) but on I875 PAT is always enabled. the GAT settings are just memory tweaks.
  • Pumpkinierre - Friday, February 20, 2004 - link

    Turn it off and see if it makes any difference. On Abit you cant run F1 or street racer PAT settings above CAS2 or on 5:4. I dont know about Turbo but it doesnt add all that much anyway.
  • Icewind - Friday, February 20, 2004 - link

    Uhhh, you wanna bet? Im running PAT at 5:4 ratio with my Corsair 3700XMS on my P4C800-E Deluxe bud at 3-4-4-8.
  • Pumpkinierre - Friday, February 20, 2004 - link

    #4 and #5 you cant run PAT with 5:4 ratio nor with memory timed higher than CAS 2. So, Trog, your best cpu is a 3.2 or 3.4. That way you get the high speed with small overclock allowing the use of DDR433 low latency BH5 chipped memory (o'clocks to 450). Amongst the cheappies, the 2.8 is the best and use OCZ 466 gold which holds CAS2 up to 420 and then 2.5 through to DDR500. Or else use the 3500 Mushkin or OCZ low latency.

    #5 I dont see why you cant get 2225 at ddr500. Those graphics cards have got 2.2ns chips and run at DDR700-1000. I'm not sure about the latency but if you lower the speed you can improve on the latency. I'm waiting and I'll buy when it comes out. All these DDR533 and 550 seem to be a rehash of the same thing and missing the low latency quality that is required for PAT to be enabled.
  • Icewind - Thursday, February 19, 2004 - link

    Condsidering its the ASUS's highest end board, they probably left the PAT on, and why you would want it off in the first place is beyond me.

    Considering the limations of the current breed of DDR chips, a 2-2-2-5 or close to that at DDR500 simply isn't plausible from a manufacturing/cost point.

    DDR2 aint looking much better either, it runs at 4-4-4-12 settings stock. So I think the days of low timing memory are going to be going the way of the do do.
  • TrogdorJW - Thursday, February 19, 2004 - link

    I'd be curious to see a roundup of various benchmarks done with the varying memory speeds and timings, sort of like what you started with by comparing 3.2 GHz at 266 MHz bus to 3.2 GHz at 200 MHz bus. Here's what I'm thinking:

    Get a 2.4C, 2.6C, 2.8C, 3.0C, and 3.2C. (Or use your P4 3.2ES, I suppose.) Then do a variety of benchmarks (i.e. not just Quake 3, SuperPi and Sandra) at reasonable settings and memory timings.

    From what you've shown in this article, a 2.4C overclocked to 3.2 GHz will outperform a 3.2C at stock bus speeds. However, it could do this with low latency 5:4 ratio or higher latency 1:1 ratio settings. What appears to be the best choice? A 2.4C would require a 266 bus to reach 3.2 GHz, where a 2.6C would "only" require a 246 MHz bus, a 2.8C would require a 229 MHz bus, and a 3.0C would need a 213 MHz bus. At those bus speeds, the 2.4 and 2.6 overclocks would need to use either lower timings or a 5:4 ratio, but the 2.8 and 3.0 could probably get 2-2-2-6 (or 2-3-3-7 timings?) with a 1:1 ratio. Also, how does PAT affect things? Did you have it enabled on the 1:1 OC and not on the 5:4 OC? I wan't sure.

    I know, it's a lot of work and may not be that useful to many. Still, it's something I would enjoy seeing when/if you get the time. Anyway, with 2.4C, 2.6C, and 2.8C all costing about the same amount right now, I'm not really sure where the best buy is. 2.4C would probably be fastest if you could get really expensive RAM to handle the high OC and the processor worked at 3.2 GHz, but do 2.6C or 2.8C overclock higher on average, due to the higher multipliers?

    Great article, though. Nice to see that low timings can still match higher clock speeds. Also, any chance of seeing a similar roundup using Athlon XP? (I would also say Athlon 64, but they don't seem to have enough OC headroom.) Athlon XP might not be able to make use of anything over DDR533 - or maybe even DDR500 - but I haven't seen any good comparisons on it.

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