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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  • james007 - Thursday, February 16, 2006 - link

    Hi, I deeply appreciate the hard work and thought that went into this article. I'm not a 'gamer' though -- I'm trying to select the fastest available mobo for software development. Visual Studio 2005 is a dog, dawg! I don't mind dropping a few hundred for speed.. so what are y'all's thoughts: what's the fastest mobo? A8R-MVP, or A8N32-SLI? Or another board?
    + I'm still trying to select the snappiest hard drive. SCSI (like, Cheetah) or Sata?

    Thanx for your advice and for lending us the benefits of your experience.
    JH
    Reply
  • htcstech - Wednesday, February 1, 2006 - link

    Apologies for my ignorance, but did you test the motherboard overclocked or as standard?
    If either OC or standard, have you posted the other results?
    Thanks
    Reply
  • superkdogg - Monday, January 16, 2006 - link

    Hey Wes,

    Did you really get that 325x9 @ 1.300 vCore like the screenshot on the first page says?

    If so, you had a fantastic setup going. I'm looking forward to getting my board (despite the numerous complaints about vCore not as advertised). I can deal with the memory issues (real or user-based) because I'm still rocking the Corsair VS with dividers anyway.
    Reply
  • tanstudio - Thursday, January 12, 2006 - link

    I have a a8r mvp and opteron 146 running stable at 2.6G with 1.45V. I can boot into 2.7G but soon windows hangged. And the max cpu voltage I can have is 1.45V with this motherboard. It would be great if the board can have 1.5-1.65 v cop voltage so my opteron 146 may have a chance to hit 2.8G with 1.5V or 1.55V core voltage. Reply
  • Beenthere - Sunday, January 8, 2006 - link

    As many people who have purchased the A8R-MVP Mobo have sadly discovered, there are some serious issues with the production Mobos that Anandtech did not experience with their review board. Specifically the Mobo does NOT provide CPU Vcore voltages above 1.40V and many if not most people who have purchased this Mobo have been unable to run memory at 1T above 250 MHz even though the same memory runs fine on other Mobos above 250 MHz at 1T with no problem. The voltage issue is serious because Asus clearly advertises the A8R-MVP for use with all socket 939 Athlon / FX / X2 CPUs, which of course is impossible as the (CG) Clawhammer core chips require a MINIMUM 1.50V, which isn't even an option on the A8R-MVP Mobo.

    After careful review of a number of factors I have a suspicion that the A8R-MVP has limited Vcore current capacity and that is why Asus has refused to provide the proper voltage options in the BIOS. I suspect after they produced the Mobo they discovered the shortcoming and so limited the voltage options because the current draw increases as you O/C the CPU, which is only possible if you can raise the voltage, in most cases. This is just my theory but if Asus could provide the proper CPU voltages for the CG core CPUs then you'd have thought after two BIOS updates they would have...

    From my perspective this is simply unacceptable as any Clawhammer based CPU requires a minimum 1.50V per AMD. Asus has advertised the A8R-MVP as being fully Athlon / FX / X2 compatible and even states in their online Tech Section that the FX-55 and 4000+ are fully supported on this Mobo - which of course they ARE NOT as they require a MINIMUM 1.50V, which is not even an option on the A8R-MVP.

    My suggestion is that people STOP BUYING THIS MOBO if you need a minimum 1.50V Vcore. Anyone who can return their A8R-MVP under warranty would be advised to do so. If you have an FX-55 or 4000+ that requires 1.50V per AMD, then you can't run it on this Mobo despite Asus' claims of fitment. That's my view of things based on what I see and I'd suggest potential purchasers of this Mobo be advised of the unusually low CPU voltage options PRIOR to purchase as you may need to return the Mobo if your CPU requires 1.50 or more volts to function properly.
    Reply
  • Wesley Fink - Sunday, January 15, 2006 - link

    Your information is not completely true - but you already know this. The vCore of the A8R-MVP varies according to the CPU installed. It does NOT stop at 1.4V with a Clawhammer. The range available varies with the CPU and is always 0.0v to 0.1v more than the default voltage of the CPU. When we tested the board Asus advised that the additional overvolt option in the BIOS added 0.2V more vCore. After measuring several boards the actual addition of the overvolt jumper is 0.1V.

    The range is not quite as wide as what we initially reported, but it is not nearly as limited as what you report. If you plan to post this in every Forum that mentions the A8R-MVP you need to at least get your facts correct. The limit is not 1.65V with a 1.45V processor, but it is alos not the 1.4V you imply. Fo most recent AMD processors increasing vCore does little for overclocking anyway. You are better off using the chipset and HTT overvolt. No doubt many would welcome a range to 1.7V, but the design of the A8R-MVP does not make that a likely prospect. I also did not need the much higher vCore to reach 325FSB in my testing.

    What I am finding in emails is about half can duplicate results I found, while the other half have difficulty getting above 250-260. It does appear there may be quite a bit of variation in the OC performance of the shipping RD480 chipsets - and that there are chipsets out there that OC well and half that don't overclock as well.
    Reply
  • dlxhammer - Tuesday, January 10, 2006 - link

    Thanks for the info Beenthere, but sadly i have already ordered this mobo, along with an x1800xt. I WAS planning on using my current cpu (amd 3500 clawhammer) and you are correct the voltage is 1.5

    Maby its time to upgrade my cpu:\ I notice the AMD dual core processors require 1.35-1.4 volts would this be a wise choice? maby ill give my current cpu a shot 1st...
    Reply
  • tmodel37 - Monday, December 19, 2005 - link

    Hi Wes,
    Since I cannot find the A8n32 SLI Deluxe anywhere, the A8n-MVP sounds great, but I already have 2 7800GT's. Where can I get the hacked drivers? I am 68 yr. old newbie, and need all the help I can get.
    Reply
  • Ryan Norton - Monday, December 12, 2005 - link

    Feedback thread:

    http://forums.anandtech.com/messageview.aspx?catid...">http://forums.anandtech.com/messageview...9&th...

    I took it up to 325HTT last night in 5MHz increments and let it run Memtest all night, still rock solid. A couple anomalous BIOS setting options, however.
    Reply
  • AllanLim - Sunday, December 11, 2005 - link

    And am proceeding wring some performance from it. Question is Wes, how were you able to get 325x9 with the current BIOS options.

    Rgds
    Reply

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