Overclocking

Asus A8R-MVP Overclocking Testbed
Processor: Athlon 64 4000+
(2.4GHz, 1MB Cache)
CPU Voltage: 1.45V (default 1.40V)
Cooling: Thermaltake Silent Boost K8 Heatsink/Fan
Power Supply: OCZ Power Stream 520W
Memory: OCZ PC3200* Platinum Rev. 2
(Samsung TCCD Memory Chips)
*The current equivalent OCZ memory is OCZ PC4800
Hard Drive: Seagate 120GB 7200RPM SATA 8MB Cache
Maximum OC:
(Standard Ratio)
246x12 (4x HT, 2.5-3-3-7)
2952MHz (+23%)
Maximum FSB:
(Lower Ratio)
325 x 9 (3x HT, 2T*, 3-4-3-8)
(2925MHz, 2 DIMMs in DC mode)
(+62.5% Bus Overclock)

Screen captures on the first page have already announced that the Asus A8R-MVP has set new overclocking records in our testing. We actually found 330 to be stable in memtest86 and booted into Windows at a little more than 330 with memory set to a DDR400 starting point. However, Windows was not completely stable at 330 and required a slight lowering to 325 (DDR650). The 325 setting was completely stable, ran our benchmarks, and ran for more than 2 days on just air cooling.

Our first efforts at overclocking the A8R-MVP ran into a road block at just over 260. We have found some Asus boards in the past that did not like overclocks to be immediately set to high values, so we started again at 250. By going up just 5 to 10FSB at a time, we were able to reach 325. Since we had no idea that we would reach such a high OC on this mainstream board, we have screen captures at every 5MHz from about 270 to 330. Our advice to overclockers on this board is to move the overclock up slowly.

*UPDATE: After further testing we have concluded that the A8R-MVP handles 1T timings only to about 260-265. Above 260-265 you will need 2T timings to reach 325 or so clock frequency. We ran into a wall at 260 and apparently the BIOS reset. The default is 2T and we didn't catch the Command Rate reset. This board uses very aggressive timings, and the 2T memory bandwidth was so fast we did not realize the board was actually running at 2T. This does not change the fact that 325 at 2T is an outstanding overclock, but it is achieved at 2T timings, and not at 1T as originally reported.

Those who don't understand overclocking or who don't want to bother will find extensive automatic overclocking options in the Asus BIOS. This allows you to set an overclock and have the board adjust the related settings. These work well for modest overclocking, but they will not allow the extreme results achieved manually on the Asus A8R-MVP.

Memory Stress Testing

The Asus A8R-MVP easily handles 2-2-2-7-1T timings at stock speed, as do almost any of the current boards for AMD Socket 939 from NVIDIA, SiS, VIA, ATI, and ULi. However, the default setting for Command Rate in the Asus BIOS is 2T, and you need to manually set Command Rate to 1T for best performance with 2 DIMMs in Dual Channel mode. Asus tells us that this was done to accommodate some memory manufacturers that had asked for a default 2T Command Rate for maximum compatibility with their memory. Once set, we had no issues using 1T command Rate with any memory that we tested.

Running four double-sided 512MB or 1GB DIMMs is much more demanding than running two DS DIMMs, and Asus did not have any extra magic here. Like every board that we have tested except the DFI RDX200, we needed to drop the Command Rate to 2T with 4 DS DIMMs. With 4 DIMMs, the A8R-MVP remained stable with the same aggressive 2-2-2-7 timings used for two DS DIMMs.

Stable DDR400 Timings - 4 DIMMs
(4/4 DIMMs populated)
Clock Speed: 200MHz
CAS Latency: 2.0
RAS to CAS Delay: 2T
RAS Precharge: 7T*
Precharge Delay: 2T
Command Rate: 2T
*7T was determined by MemTest86 benchmarks to deliver the widest bandwidth with the ATI Rx480/482 chipset. While the board would operate at tRAS of 5T or lower, all benchmarks were run at 7T.
Basic Features: Asus A8R-MVP Test Setup
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  • Avalon - Wednesday, November 23, 2005 - link

    Wesley, just for giggles, can you set a RAM divider and drop your CPU multiplier down to 7x, and see how high the HTT can reach stably? That would be nice to see.
  • n7 - Wednesday, November 23, 2005 - link

    I may have just founds my next motherboard!

    As long as prices do come to the level of a mainstream mobo, this looks very good.

    I have to admit, until the A8N32-SLI Deluxe, & now this, i was extremely unimpressed with all Asus A64 motherboards.

    Now the last two i've seen from Asus look very good :)
  • fitten - Wednesday, November 23, 2005 - link

    quote:

    It is very important that users change the default 2T Command Rate to 1T for best performance.


    I see this a lot (particularly on AnandTech) and have yet to see any *real* benchmarks that show this change results in anything more than a 1% to 2% performance gain, which is typically within the statistical margin of error for the benchmarking performed by most review sites. Are there any definitive benchmarks (that are statistically significant) that show more of a gain than this?
  • Wesley Fink - Wednesday, November 23, 2005 - link

    You have seen this a lot on AT and any site that specializes in performance and overclocking. Memtest86 is a standard test used in the memory industry to test performance. It shows a 5 to 10% increase in performance at 1T compared to 2T - depending on CPU speed and memory frequency. Similar increases are reported by SiSoft Sandra Unbuffered and Everest, which also measure memory bandwidth.

    Memory is only one small part of total performance, and in gaming 1T only increases framerate 1% to 5% depending on the game and equipment used for testing. You are correct that this won't be noticed by most end users, but if you are aiming for absolute top performance in gaming or competetive benchmarking this does matter. We covered this pretty thoroughly with test results in a memory piece several months ago.
  • Live - Wednesday, November 23, 2005 - link

    Very nice review and a nice find!

    I would have loved to have seen the ASRock 939Dual-SATA2 included in the benchmarks. Why? It is just as close in price as many other boards and frankly cater to sort of the same user group. This would also show what can be had in the different price groups.

    I also find this quote a bit strange
    quote:

    But based on the Asus expectations being set very low for this board, and the genuine surprise that Asus expressed when we reported our results, I would venture to say that what we found is not a fluke.


    I would think that ASUS having low expectations on this board and they being genuinely surprised would indicate that there internal testing does not show the same results as your sample does. Thus indicating it is indeed an over performing sample. This possibility seems just as likely anyway. What I am missing?
  • Wesley Fink - Wednesday, November 23, 2005 - link

    Asus does extensive overclocking tests on their top-line boards aimed at that market. They generally know how they will perform in overclocking. They do more modest tests on mainstream boards. It is my opinion it never occured to Asus that the A8R-MVP might be a monster overclocker until I reported my results back to them. Once I did, Asus was very helpful in adding additional options to BIOS that I suggested would be welcomed by overclockers. Some components limit what Asus can add, but they had added additional options that could be added.

    We do have a very good working relationship with Asus. As an example the first Asus A8N-SLI Premium boards (without the paddle) were supposed to be top-end. Our pre-production samples turned out to be very poor overclockers due to the automatic switches and Asus decided to rework the board rather than bring a mediocre board to market. The revised Premium came about 8 weeks later and we confirmed it was an oxcellent overclocker and a good performer. That is the board Asus brought to market.
  • Live - Wednesday, November 23, 2005 - link

    Thanks for the clarification. I think I got what I was missing. In that light this board does look like a true gem in disguise.
  • nvidia4ever - Wednesday, November 23, 2005 - link

    Is there a reason why the X1800XT was not tested? By chance, did you test the board with a Opteron 148? I could see this combination being great together considering how well both overclock. That would be a killer package at $350. When will the board be available?
  • Wesley Fink - Wednesday, November 23, 2005 - link

    The motherboard lab does not a X1800XT for benchmarking, a fact we point out to ATI whenever we get the opportunity. ATI is still having X1800XT supply problems and they have promised we will have cards for testing as soon as they are available for sampling.

    We have to wonder aloud if we have had so much trouble getting X1800XT for testing, what chance does a "mere mortal" have to buy an X1800XT. We can only say we're glad ATI does not appear to have motherboard chipset supply issues, because the video card situation is horrendous.



  • nvidia4ever - Wednesday, November 23, 2005 - link

    There are several x1800xt cards available here - http://www.newegg.com/Product/ProductList.asp?Manu...">x1800xt cards Is ATI just screwing around with you guys? Can this board run nvidia sli cards?

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