Selection of CPU for ASUS P4P800-X and -SE

  Catastrophe 10:32 10 May 09
Locked

This subject arises out of my faulty mobo thread. Since we seem to have narrowed the problem to the CPU it seems pointless to wade through all the other discussion.

Basically I could not get any display with a mobo contained in a case I bought. Fair enough - I bought only the case. Since PSU, RAM (recommended by and bought from Crucial), new and CPU bought from reliable guy on eBay (he wanted 2.8 MHz and got 1.8MHz by mistake so CPU unused). Hence I blamed mobo and replaced it with a P4P800-SE which apparently has the same requirements. However the problem persisted - no POST no display.

On doing some research I am wondering if CPU or CPU/RAM combination is causing the problem.

In "The Complete PC Upgrade Handbook 2009" page 33 it states:
"Another compatibility issue that affects only Intel processors is the Front Side Bus (FSB)speed. ... different Intel processors require different FSB speeds. ... Your motherboard will support only certain FSB speeds."
I can find no mention in the ASUS manual which appears to suggest (to me) that any P4 478 would work.

The P4P800-X supports PC 3200, 2700 and 2100 and the FSB is 800MHz. I believe the processor I bought is 400MHz. It was advertised as
1.8GHz 256/400/1.75v.

In the section on memory the manual states:
"CPU FSB DDR DIMM Type Memory Frequency
800 MHz PC3200/PC2700/PC2100 400/320*/266 MHz
533 MHz PC2700/PC2100 333/266 MHz
400 MHz PC2100 266 MHz
*When using 800 MHz FSB CPU, PC2700 DDR DIMMs run only at 320MHz"

I have 2 x 1GB RAM fitted in the blue slots. Does the above mean that if the CPU is 400MHz, I can only use PC2100 266MHz?

Is this maybe why I am getting no post? I have ordered an 800MHz CPU - do you think this might cure the problem?

Apologies for the length but I wanted to get in all relevant info.

Any ideas please?

:)

  Quiller. 10:45 10 May 09

Thats right. If you use a 400Mhz fsb cpu you use pc2100 or you could try, long shot, to alter the speed in the bios from spd to 133/266Mhz ram. Save and exit.

But if you get no post, thats out.

Do you have a small stick of pc2100 you could boot with to alter the bios. It might work.

  Catastrophe 10:49 10 May 09

BSOD

Many thanks for your comment - I will have a look around as I do have lots of old memory.

Do you think the 800MHz FSB will be OK with 2-4 GB RAM?

  Quiller. 10:51 10 May 09

Have you reset the cmos via jumper or battery?

  Catastrophe 10:53 10 May 09

BSOD

"Have you reset the cmos via jumper or battery?"

I did with the first motherboard (removing battery) but not with the second.

  Quiller. 10:57 10 May 09

800MHz FSB will be OK with 2-4 GB.

Do you mean will a 800Mhz cpu run with 2-4Gb of PC3200 ram? The manual says it will, but if you use 4Gb you will see just over 3Gb.

If you use pc2700 with a 800Mhz cpu, the memory will just run at 320Mhz as per manual.

  Quiller. 10:59 10 May 09

I did with the first motherboard (removing battery) but not with the second.



look in the manual for the cmos jumper, page 1-15, the jumpers next to the battery. Clear the cmos and put it back in the run position, then try.

  Catastrophe 11:02 10 May 09

BSOD

"Do you mean will a 800MHz cpu run with 2-4Gb of PC3200 ram?" Yes.

"The manual says it will, but if you use 4Gb you will see just over 3Gb."

Will it use 4GB and just show just over 3GB, or will it use only just over 3 GB? There is provision for matched pairs and hyperthreading so would it be worthwhile to buy 2 more 1GB RAM?

  Catastrophe 11:05 10 May 09

"look in the manual for the cmos jumper, page 1-15, the jumpers next to the battery. Clear the cmos and put it back in the run position, then try."

Just seen this - will give it a try.

  Catastrophe 11:16 10 May 09

Slight problem. I have the -SE fitted at the moment so I will have to download the manual for that. There are no jumpers in that position.

On the -X there are two vertical rows of 3 and they are thus:

.|
|.

only in line if you see what I mean. Left bottom 2 joined, Right top 2 joined.

I will download manual for -SE rather than swap it all over right now.

  Catastrophe 11:23 10 May 09

On looking carefully with a magnifying glass there is a 3 pin jumper set up and to the right of the battery with CLRT nearby. 1-2 default 2-3 clear.

Do I just change to 2-3 : power up and leave a short while, then power down and reset 1-2?

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