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667mhz DDR2 - running at 200mhz ?!?


rohan

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I just bought two 1gb sticks of Corsair PC2-5300, DDR2 667mhz ram.

 

My motherboard is an ASUS P5VDC-MX. It supports up to 533mhz ram. So this 667 should downclock to 533.

 

Ram runs fine, but upon consulting CPU-Z, the memory tab indicates "199.5 MHz" for the "Frequency" number on the "Memory" tab.

 

Further, it indicates SINGLE channel.

 

Two questions:

1) Why is my ram only running single channel?

2) Why is it only running at 200mhz ?

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I just bought two 1gb sticks of Corsair PC2-5300, DDR2 667mhz ram.

 

My motherboard is an ASUS P5VDC-MX. It supports up to 533mhz ram. So this 667 should downclock to 533.

 

Ram runs fine, but upon consulting CPU-Z, the memory tab indicates "199.5 MHz" for the "Frequency" number on the "Memory" tab.

 

Further, it indicates SINGLE channel.

 

Two questions:

1) Why is my ram only running single channel?

2) Why is it only running at 200mhz ?

 

I echo the RAM GUY's questions.

 

Also, DDR2-533 memory does not actually run at 533MHz. Due to "double-pumping," your memory's actual clock speed frequency should be close to 266 MHz. But because you put both of your memory sticks in the same channel, your memory defaulted to DDR2-400 speed and in single-channel mode due to the additional loading on the motherboard's memory controller.

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Good follow-up questions. As reported by CPU-Z:

 

CPU Speed: 2800 MHz

Multiplier: x 20.0

Bus Speed 140 MHz

Rated FSB 560.0 MHz

 

The memory is in slot #1 and slot #2. There are ONLY two slots for DDR2 on this board. There are also two slots for DDR1 on this board - which are empty.

 

Thanks for the explanation about memory speeds in single channel. My questions now would be:

 

1) Why is my ram running single channel?

2) Why is my ram running at 200mhz, not 266?

 

and perhaps a 3rd question - why is my bus speed 140 MHz? - isn't that really slow for a modern system?

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Judging by your multiplier, you actually have a 2.66GHz/533FSB processor that's been overclocked on your motherboard. If that processor had an 800FSB, then its actual clock speed would have been a ridiculous (for your CPU core stepping) 4GHz! (Remember, all Intel processors except for some of the EE series have permanently locked multipliers.)

 

In addition, just because you have two memory modules of the same model number doesn't mean that the two modules are exactly identical: If you bought the two modules separately (as opposed to a twin-module kit), there is a very good chance that one module will be slightly different from the other. (With the Value Select line, the ICs, PCBs and SPDs used are always subject to change.) And even that may default your system's memory controller to single-channel-only mode.

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Right - forgot to mention I changed the FSB from 133 to 140. But I just did that a few seconds ago. Typically it's a 133 FSB, 2.66 ghz (it's a dual core Pentium D 805)

 

The memory was purchased as a dual channel kit. It IS value ram, but if it's sold as a kit, should it not still be a dual channel capable pair?

 

 

In regards to the motherboard - I don't see any info anywhere online indicating dual or single chanel. HOWEVER, it does say that it supports 533 mhz DDR2. Here's my thinking - if 533mhz is ONLY achieved using dual chanel ram (that is natively 266mhz per stick), then there would be NO WAY that a motherboard could support 533mhz DDR2, unless it supported dual chanel.

 

So it must, no?

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Right - forgot to mention I changed the FSB from 133 to 140. But I just did that a few seconds ago. Typically it's a 133 FSB, 2.66 ghz (it's a dual core Pentium D 805)

 

The memory was purchased as a dual channel kit. It IS value ram, but if it's sold as a kit, should it not still be a dual channel capable pair?

 

 

In regards to the motherboard - I don't see any info anywhere online indicating dual or single chanel. HOWEVER, it does say that it supports 533 mhz DDR2. Here's my thinking - if 533mhz is ONLY achieved using dual chanel ram (that is natively 266mhz per stick), then there would be NO WAY that a motherboard could support 533mhz DDR2, unless it supported dual chanel.

 

So it must, no?

 

Actually, you're confusing "dual-channel" with "double data rate." "Dual-channel" actually ties the two channels of a memory controller together in unison so that the two separate 64-bit memory banks get read as one 128-bit bank. Unfortunately, the P4M800 Pro chipset on your motherboard supports only single-channel memory controller operation - and using more than one stick of memory on your motherboard may drop your memory speed down to DDR2-400.

 

In addition, have you ever thought of the possibility that your DDR2-667 rated sticks lack any SPD programming at all whatsoever for any speed besides the single DDR2-667 speed? If that's the case, with your motherboard the memory speed will default to DDR2-400 speed in order to protect the system.

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Truthfully - I hadn't thought of any of that. I'm not really up to speed on a lot of the current hardware workings. I'm about 2 or 3 years outdated knowledge-wise :(

 

I'm aware of the fact that my motherboard is low-end, so I don't expect miracles. Basically, if I'm running at the limit of my board, I'm fine with it - I just wanted to make sure I'm not running below what I could be at with my existing hardware.

 

Next on my list to upgrade is the board - but first I needed the DDR2, so this is really just a stop-gap until I can justify a new board. (Anyone want to help me justify a new board??? What might I gain from a better board with my existing chip.... ?)

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