[churin]

I have just built a new system with Gigabyte GA-MA74GM-S2 Rev 1.0, Athlon 64x2 4800 (ADO4800IAA5D0) and 2GB x2 DDR2 800. When it booted for the first time, the core speed was set for 1000MHz. I reviewed the BIOS and found the multiplier was set for x5. I looked for x12.5 but it was found that x12 was the maximum available multiplier. I selected x12 and now the CPU is running at 2400MHz. Version of the BIOS is F1 which supports this CPU according to info published at the vendor's website.
What could be the cause of this problem?

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The 4800 comes in four different types that have two different speeds - 2400Mhz and 2500Mhz. The difference is in the size of the L2 cache, which should be printed on the packaging of the CPU box if you bought it retail. The 1Mb L2 cache CPUs run at 2400Mhz, while the 512k cache is 2500Mhz.

[Neil Jones]

The 4800 comes in four different types that have two different speeds - 2400Mhz and 2500Mhz. The difference is in the size of the L2 cache, which should be printed on the packaging of the CPU box if you bought it retail. The 1Mb L2 cache CPUs run at 2400Mhz, while the 512k cache is 2500Mhz.

[churin]

I bought the mobo, a pair of the RAM sticks and the CPU. I let a technician at the store mount the CPU and the RAM sticks on the mobo and check if the system POSTs. Thus I never had a chance to see the part number marking on the CPU. The receipt shows the part number of ADO4800IAA5D0 which is one of those Brisbane and this is what I thought I would be getting.

Is there any way to determine the part number without seeing the marking on the CPU?

[Troy]

Are you not able to find the retail box?

You could try running CPU-Z, it should give you all the information on your processor.

Troy

[churin]

Are you not able to find the retail box?

You could try running CPU-Z, it should give you all the information on your processor.

Troy

It did not come in a box. It is a cpu alone and heatsink and fan not included.

The CPU-Z shows in the NAME field, AMD Athlon 64 X2 4800+, and in the Specification field, AMD Athlon™ 64 X2 Dual Core Processor 4800+. In the Code Name field, Brisbane is shown. The part number is not shown anywhere so that which one of the Brisbanes can not be determined.

My question is if what the CPU-Z indicates is that authoritative and reliable? My understanding is that what Windows or any system utility says is dependent on what the BIOS does: CPU-Z simply takes what the BIOS says or guesses about the cpu. For example, my another PC is a dual Opteron 252 system, and the BIOS failed to detect what the cpus are or "AMD processor model unknown" then CPU-Z says the same.

I wonder exactly how the BIOS determines what an installed cpu is. Without this info it can not correctly set the bus speed, multiplier, etc. Could anyone shed light on this?

Edited by churin, 23 February 2009 - 08:29 AM.

[Neil Jones]

CPU-Z tells you what the board already knows.
The processors announce they've got such-and-such a L1 cache, L2 cache, etc but the board doesn't know what name it's called and therefore it claims it's an unknown processor. It's like meeting somebody in the street and you immediately work out they've got red hair, blue jeans, looks like they spend too much time down the pub, etc, so to you he's a new bloke with no name. You'd just call him "this bloke".

On the initial problem, your part number traces back to this processor:
http://products.amd....tail.aspx?id=47

What does CPU-Z tell you about your L1 and L2 cache? That processor with that part number should run at 2500Mhz with a 512K L2 cache.

[churin]

I understand that the BIOS automatically set the rated core speed for a given cpu. In order for the BIOS to do this it must be able to detect what the CPU is, otherwise it can not pick the correct bus speed and multiplier to set the rated core speed. I thought the BIOS itself go and get the necessary info rather than wait for being told by an intermediary which you refer to as "board".

Anyway you imply that the BIOS may fails to get the necessary info. Is this the case with my problem? Or, the CPU is not what is shown on the sales receipt? I hate to remove the heatsink just to take a look at the marking on the CPU. Can I say that the CPU is either Toledo or one of those Windsors and none of the Brisbanes ?

[Neil Jones]

It is entirely possible the information on the sales receipt is wrong. These are generated by humans and humans are not infallible.
The only way you will know for sure is to take the heatsink off, remove the thermal paste and read the numbers on the core of the processor. When you replace it new thermal paste will be needed.

[churin]

As I stated in my original post, the BIOS set the core speed for 1000MHz. This could be a ground to suspect the mobo including the BIOS. Even the CPU is a wrong one the core speed was found to be settable for 2400MHz. So, it does not seems to matter what CPU is on the mobo. I am thinking of returning the mobo to the store.
Any comment is appreciated.

[churin]

The problem was resolved by updating the BIOS v. F1 to v. F3. The "CPU Support List" published at the mobo vendors's website indicated that F1 supported the CPU. But I decided to try reflashing the BIOS before returning the mobo to the store.

The new BIOS failed to set the core speed correctly as did the old BIOS, but this time I found that x12.5 became available on the new BIOS. I manually set it for x12.5 and 2500MHz core speed finally realized.
I reset the BIOS for AUTO selecting the multiplier, or reloaded "Optimized Default Sets" but the BIOS keep setting the core speed corrctly since.

Thanks everyone for trying to help me.