DDR memory - bios shows less speed than actual

[samrat_rao]

Hi,

I have a 5 yr old desktop with a P4 2.66GHz. The board is D915GLVG with 4 DDR slots of 1Gb max capacity each.

I have filled all the DIMM slots as follows:
1) 2 x 1024Mb in 2 slots
2) 2 x 256Mb in the other two slots

All the memory modules are 400MHz. 3 sticks are from the same vendor, say A, ie 2 x 1024Mb and a 256Mb. The 256Mb one is single sided while the 1024Mbs are double sided. When the ones from vendor A are used, the bios correctly shows system memory speed as 400MHz.

The 256Mb from the other vendor, say B, is double sided. If the vendor B's 256Mb is used alone then too the bios shows 400MHz. But when A and B are used together in any combination the bios shows 333MHz only as system memory speed.

The total installed capacity is correctly shown in the bios, just the speed is 333MHz instead of 400MHz. Any idea why? The OS is correctly functioning.

Also the processor is capable of handling only 333MHz.

What do you guys feel? Thanks.

 

[Aastii]

Hi,

I have a 5 yr old desktop with a P4 2.66GHz. The board is D915GLVG with 4 DDR slots of 1Gb max capacity each.

I have filled all the DIMM slots as follows:
1) 2 x 1024Mb in 2 slots
2) 2 x 256Mb in the other two slots

All the memory modules are 400MHz. 3 sticks are from the same vendor, say A, ie 2 x 1024Mb and a 256Mb. The 256Mb one is single sided while the 1024Mbs are double sided. When the ones from vendor A are used, the bios correctly shows system memory speed as 400MHz.

The 256Mb from the other vendor, say B, is double sided. If the vendor B's 256Mb is used alone then too the bios shows 400MHz. But when A and B are used together in any combination the bios shows 333MHz only as system memory speed.

The total installed capacity is correctly shown in the bios, just the speed is 333MHz instead of 400MHz. Any idea why? The OS is correctly functioning.

Also the processor is capable of handling only 333MHz.

What do you guys feel? Thanks.

Some motherboards will only operate memory at higher frequencies when a certain number of DIMM slots are populated.

For instance, on newer boards, some will support 1333MHz DDR3 with all 4 slots full. They will also support 1600MHz, but only when 2 slots are full, so if you put in 4 sticks of 1600MHz memory, the board will automatically underclock the RAM to the lower speed that allows the system to run with all 4 DIMM slots populated.

You could try "overclocking" the memory back to 400MHz, but if you do this the memory may need a slight voltage bump, as may the northbridge

 

[samrat_rao]

Some motherboards will only operate memory at higher frequencies when a certain number of DIMM slots are populated.

For instance, on newer boards, some will support 1333MHz DDR3 with all 4 slots full. They will also support 1600MHz, but only when 2 slots are full, so if you put in 4 sticks of 1600MHz memory, the board will automatically underclock the RAM to the lower speed that allows the system to run with all 4 DIMM slots populated.

You could try "overclocking" the memory back to 400MHz, but if you do this the memory may need a slight voltage bump, as may the northbridge

Hi,

Thanks for the reply. But a couple of points:

1) Even if i do not populate all the slots but use only the 256Mb of vendor B with, say, the 256Mb of vendor A (ie only 2 of 4 slots filled) then also the bios shows 333MHz although individually the memory modules show 400MHz in the bios.

2) Additionally, i also have access to another system with the same board (D915GLVG) where all the DIMM slots are filled with 400MHz of different vendors. But the bios correctly shows 400MHz.

---> By vendors i mean different brand names although the chips may or may not have the same label like 'hynix'

My desktop has a P4 2.66GHz processor that can only support 333MHz while the other one has a P4 3.00GHz processor that can support 400MHz, but then why should the bios show differences? Are bios updates necessary to solve this issue? Any risks with bios upgrades?

 

[linkin]

I'm guessing that some of the sticks are 333mhz while the others are 400mhz. When a computer two different speeds of RAM it will always use the lower speed, otherwise the RAM won't be stable because of the increase in frequency.

For example, If one of my RAM sticks was 800mhz and the other was 533mhz, the BIOS would detect the difference and make the 800mhz stick run at 533mhz. This happens on any computer and the speed of the memory is irrelevant, it wall always use the slowest one.

Say I have 3 sticks of memory, one at 1066mhz, one at 800mhz and one at 533mhz. As before all the sticks would be forced to use the slowest speed (533mhz) which could cause some bottlenecking.

To confirm this you can turn off the computer, unplug it from power, remove the side panel (touch a bare metal part of the chassis before touching any components) have a look at the RAM sticks and see what they are rated for.

 

[Cromewell]

It's because of your CPU's FSB. You can only use DDR400 on that board if your CPU runs at 200MHz, yours is 133MHz.

 

[Aastii]

I'm guessing that some of the sticks are 333mhz while the others are 400mhz. When a computer two different speeds of RAM it will always use the lower speed, otherwise the RAM won't be stable because of the increase in frequency.

All sticks are 400MHz, as he said. All sticks show 400MHz when alone, but only 333 when 2 or more are in, as he said.

It's because of your CPU's FSB. You can only use DDR400 on that board if your CPU runs at 200MHz, yours is 133MHz.

I thought that at first, however then why would it show 400MHz with just 1 brand, but not when there are multiple brands together.

What are the timings on both sets of memory?

 

[Cromewell]

All sticks are 400MHz, as he said. All sticks show 400MHz when alone, but only 333 when 2 or more are in, as he said.



I thought that at first, however then why would it show 400MHz with just 1 brand, but not when there are multiple brands together.

What are the timings on both sets of memory?

I'm thinking it's because of dual channel support. DDR400 in dual channel is faster than the system bus where DDR400 in single channel is not.

 

[samrat_rao]

Hi,

Once again thanks for all your replies.

What are the timings on both sets of memory?

Could you clarify what you mean by 'timings'? i'm not too much of a hardware guy. All are PC 3200 if thats what you mean.

I'd also like to report a couple of extra things:

---> This is with all 4 slots filled...

1) I removed the odd memory stick out (the 256Mb 400MHz of vendor B) and fitted this slot with another vendor's (not A or B) 400MHz stick of 1Gb and 512Mb in 2 separate trials --- so now there are 400MHz sticks again of 2 different vendors --- and viola even with all 4 slots full the board showed 400MHz.
---> So only the 256Mb one is likely the problem guy.

---> Now i have a couple of Linux distros installed. So i used the Memtest86 option to check the rams individually. this is what the test showed as one of its parameters for the rams (all other parameters were same) :
The problem guy had a different CAS (i donno what it means) rating. The odd guy from vendor B had the rating as 2.5 - 4 - 4 - 10 wheras all the others had the rating as 3 - 3 - 3 - 8. I just came to know that lower numbers are better.

So what do you guys suggest? I doubt that the person from whom i purchased the 256Mb ram will take it back as he too would not know what this means and neither will i sound too convincing.

So tell me, will keeping the odd guy with the others cause problems? Will there be any overall speed loss? Why does a lower CAS of the 256Mb of vendor B reduce the memory speed as shown in the bios when in fact lower values are better?

 

[Aastii]

You just answered your own question, timings = CAS latencies

Go to your BIOS, set the timings all the same if you can, then see what your system shows

 

[samrat_rao]

You just answered your own question, timings = CAS latencies

Go to your BIOS, set the timings all the same if you can, then see what your system shows

Hi,

I changed these settings in the bios: All timings as: 3 - 3 - 3 - 8 and the speed as 400MHz.

So only the odd one out --- 256Mb DDR with 2.5 - 4 - 4 - 10 was forced to work as 3 - 3 - 3 - 8.

Since during 'auto' settings the bios adjusted the figures as 2.5 - 4 - 4 - 8 and 333MHz, will the manual settings harm the DDRs? Which is a less strain on the rams: 3 - 3 - 3 - 8 or 2.5 - 4 - 4 - 10 or 2.5 - 4 - 4 - 8? Is it good to adjust the RAM speed as lower than designed/tested values?

 

[Aastii]

Hi,

I changed these settings in the bios: All timings as: 3 - 3 - 3 - 8 and the speed as 400MHz.

So only the odd one out --- 256Mb DDR with 2.5 - 4 - 4 - 10 was forced to work as 3 - 3 - 3 - 8.

Since during 'auto' settings the bios adjusted the figures as 2.5 - 4 - 4 - 8 and 333MHz, will the manual settings harm the DDRs? Is it good to adjust the RAM speed as lower than designed/tested values?

Should be the other way round because it works opposite to logic. You would think making the numbers lower would make it sloewr, when infact it is the opposite, because it is less time for and between cycles. If it is stable though, as in you aren't getting BSODs or your system hanging, then leave it as is, you wil get a tiny, and I mean very very very tiny, increase in performance

Did that make it show all of the memory?

 

[samrat_rao]

Ya i read somewhere that lower CAS latencies are better, but i meant to ask about the data rate. So even if 333MHz gives lower performance than 400MHz, is using 333 a less straining option than the 400MHz that is specified for each of the sticks?

I ask because the bios automatically adjusted it as 333MHz. But since the system did not hang till now, i suppose the values i used are acceptable.

And the full memory was always shown ie 2 X 1024Mb + 2 X 256Mb; the speeds and timings were the problem when the new 256Mb ram was introduced.