Newb question about FBS and my RAM

[Openupitsdave]

Well I know a few things about RAM but not enough apparently..
I have a mobo that is 1333/1066/800 MHz......The RAM is 4x1Gb PC2-5300 which in CPU-Z says its 333mhz (which would actually be 667mhz or something like that, correct?).OK, moving along..

CPU-Z says my rated FBS is running at 1066mhz and the bus speed is 266mhz... This is where im sort of confused.. Shouldn't it be running at 1333mhz since I have 4x1Gb 667mhz RAM installed? (4x333=1333) Do I have to manually set my FBS to 1333mhz to fully utilize the RAM I have installed? Or is my current understanding of how RAM works completely wrong?

Ultimately, im trying to understand RAM/mobo relationship because Im planning a RAM upgrade and possibly overclocking my CPU.. I was told my mobo doesnt like to be OC'd...could anyone confirm that? Its an Asus IPIBL-LB. Im basically trying to figure out if I should stay with pc2-5300 or switch to pc2-6400 RAM

 

[spooky2th]

Your memory advertised speed is 667Mhz. 333Mhz at the double data rate is correct for 667MHz memory. Your memory is running at the correct speed.

Searching, I could not find much about that MB. The pc2-6400 ram is 800MHz. Don't know if your MB would support that ram or not. You probably will not notice much difference between the 800MHz and the 667MHz ram anyways.

 

[Openupitsdave]

It supports 6400..

Can anyone explain why CPU-Z shows a 1066 fbs rating/266 bus speed? How does my RAM tie in with those numbers?

lol@ your profile pic..

 

[Pinhedd]

Well I know a few things about RAM but not enough apparently..
I have a mobo that is 1333/1066/800 MHz......The RAM is 4x1Gb PC2-5300 which in CPU-Z says its 333mhz (which would actually be 667mhz or something like that, correct?).OK, moving along..

CPU-Z says my rated FBS is running at 1066mhz and the bus speed is 266mhz... This is where im sort of confused.. Shouldn't it be running at 1333mhz since I have 4x1Gb 667mhz RAM installed? (4x333=1333) Do I have to manually set my FBS to 1333mhz to fully utilize the RAM I have installed? Or is my current understanding of how RAM works completely wrong?

Ultimately, im trying to understand RAM/mobo relationship because Im planning a RAM upgrade and possibly overclocking my CPU.. I was told my mobo doesnt like to be OC'd...could anyone confirm that? Its an Asus IPIBL-LB. Im basically trying to figure out if I should stay with pc2-5300 or switch to pc2-6400 RAM

There are 4 different numbers which you should be aware of:

1. The FSB frequency. This is the frequency of the periodic clock signal for the front-side bus. It is 266Mhz in your machine.

2. The FSB data transfer rate. This is the rate at which data is transferred on the FSB. The FSB transfers data on all four corners of the clock, this is also known as quad-data-rate or quad-pumped. This is 1066 megatransfers per second against a 266Mhz FSB reference clock, or 1066MT/s. Many programs and marketing geniuses phrase this as 1066Mhz, this is incorrect.

3. The DRAM IO bus frequency. This is the frequency of the period clock signal between the DRAM controller and the DRAM integrated circuits on the DRAM modules (DIMMs). On your machine this is 333Mhz.

4. The DRAM data transfer rate. This is the rate at which data is transferred to/from the DRAM ranks on your memory modules. DDR-SDRAM transfers data on both the rising and falling edges of the clock cycle, this is also known as double-data-rate. This is 667 MT/s against a 333Mhz DRAM reference clock.

The DRAM clock is derived from the FSB clock through a PLL which multiplies, divides, and synchronizes one or more output signals against an input signal. The 333Mhz DRAM clock is generated by multiplying the 266Mhz FSB clock by four, and then dividing it by three for a total of 1.25x clock multiplication; this is also known as a 4:3 clock ratio.

If you wish to use DDR2-800 modules (PC2-6400) you will have to increase the DRAM bus clock to 400Mhz from 333Mhz. You can do this either by increasing the FSB from 266Mhz to 333Mhz while maintaining the 4:3 ratio, which will also overclock your CPU accordingly, or preserve the 266Mhz FSB clock and generate a 400Mhz DRAM clock by changing the ratio from 4:3 to 3:2 which will multiply 266Mhz by 1.5 to yield 400Mhz.

 

[Openupitsdave]

Thanks Pinhedd! One question...Will it be better to increase my FBS to 333mhz and keep the 4:3 ratio...or will I get the same performance results if I keep it at 266mhz and change ratio to 3:2?

I mostly understood the rest of what you said...Ill have to research more into it to get my head fully wrapped around it..
I AM running the correct RAM setup for my current FBS rating/bus speed, correct? Only if I decide to upgrade I will have to adjust clock speeds eh?
I will have to look into if I could succesfully overclock from 266 to 333...

Thanks again buddy

 

[Openupitsdave]

Another thing... why would I need to overclock my FBS speed in order to use pc2-6400 when my mobo supports it (6400)? Does it mean its use-able but just wont work at its full potential unless I OC?

 

[Pinhedd]

Thanks Pinhedd! One question...Will it be better to increase my FBS to 333mhz and keep the 4:3 ratio...or will I get the same performance results if I keep it at 266mhz and change ratio to 3:2?

I mostly understood the rest of what you said...Ill have to research more into it to get my head fully wrapped around it..
I AM running the correct RAM setup for my current FBS rating/bus speed, correct? Only if I decide to upgrade I will have to adjust clock speeds eh?
I will have to look into if I could succesfully overclock from 266 to 333...

Thanks again buddy

Another thing... why would I need to overclock my FBS speed in order to use pc2-6400 when my mobo supports it (6400)? Does it mean its use-able but just wont work at its full potential unless I OC?

The G33 chipset which is used in your motherboard has native support for 1333 MT/s FSB (333Mhz). Increasing the FSB to 333Mhz would not constitute overclocking from the perspective of the chipset, but your CPU will be overclocked by the corresponding amount. This can be useful on some microprocessors that have locked multipliers.

My favourite example is the Core 2 Quad Q6600. It's a 2.4Ghz chip designed around a 266Mhz FSB. The 2.4Ghz clock is generated by a PLL that multiplies the 266Mhz FSB by 9x to yield 2.4Ghz. The actual value is programmable, and can accept values of 6, 7, 8, and 9, but not values above 9 as only more expensive chips can do that. Increasing the FSB from 266Mhz to 333Mhz will overclock a Q6600 from 2.4Ghz to 3.0Ghz. 9x266Mhz becomes 9x333Mhz. This was considered to be a "free" overclock, and was very popular given that most Q6600 chips didn't require much coercing to reach 3.0Ghz beyond a minor voltage increase at worst. An alternative would be to drop the multiplier from 9x to 8x which would yield a more mild overclock of 2.66Ghz.

If your motherboard natively supports DDR2-800 it should have the appropriate ratios to generate the 400Mhz DRAM clock from all supported FSB clocks. The G33 chipset supports 200/266/333Mhz FSB and 333/400Mhz DRAM, so no overclocking should be necessary. In most cases, if you do replace the PC2-5300 memory with PC2-6400 memory it should automatically pick it up and configure it for DDR2-800 speeds.

 

[Openupitsdave]

ahh OK so the PC will OC itself by adjusting the multipliers to accommodate the 6400 ram...gotcha..

In my case..I have a C2Q Q6700 that is 2.66ghz that I want to OC... what would be your recommended route? Should I OC the FBS freq or up the multipliers?? I think ill stay with the 333mhz ram for now unless OCing really needs 400mhz ram for it to perform amazingly..

I want to get it around 3.0ghz or 3.2...seems like nice round, safe numbers... I might get a new cooler if I need it..

My multipliers go from 6x to 10x... so if my FBS is 333mhz...I will get 3.33ghz??? Or if I use 9x333 I could get about 3.0ghz...hmmmm. I think im understanding this...sorta

 

[Pinhedd]

ahh OK so the PC will OC itself by adjusting the multipliers to accommodate the 6400 ram...gotcha..

In my case..I have a C2Q Q6700 that is 2.66ghz that I want to OC... what would be your recommended route? Should I OC the FBS freq or up the multipliers?? I think ill stay with the 333mhz ram for now unless OCing really needs 400mhz ram for it to perform amazingly..

I want to get it around 3.0ghz or 3.2...seems like nice round, safe numbers... I might get a new cooler if I need it..

My multipliers go from 6x to 10x... so if my FBS is 333mhz...I will get 3.33ghz??? Or if I use 9x333 I could get about 3.0ghz...hmmmm. I think im understanding this...sorta

Computers will never OC themselves. They will (usually) automatically configure themselves for the highest commonly supported standard operating frequencies and data rates. It will alter the clock rates appropriately, but not take them above what is specified as standard by the manufacturer.

Your C2Q Q6700 uses a native FSB interface frequency of 266Mhz, but your motherboard supports 200Mhz/266Mhz/333Mhz. On power up it reads information from the CPU's factory-programmed configuration data and uses this information to configure the rest of the platform. If you insert a Pentium 4/D microprocessor it will configure the FSB for 200Mhz by default. If you insert a first generation Core 2 microprocessor it will configure the FSB for 266Mhz, and if you use a second generation Core 2 microprocessor it will configure the FSB for 333Mhz. There are some budget models which are typically specced lower, and some extreme models which are specced higher but the general trend is sound for most consumer models.

If you wish to overclock your Q6700, you can do it in three stages. First, increase the FSB from 266Mhz to 333Mhz and knock the CPU multiplier down from 10 to 8. This will preserve the CPU's operating frequency of 2.66Ghz, but will increase the CPU's bus interface. Even though the CPU will run at the same frequency, the bus interface is taken out of spec on the CPU side (the motherboard is tested for 333, the CPU is not), and it is technically being overclocked. You must also reconfigure the DRAM ratio from 4:3 to 1:1, this will generate a 333Mhz DRAM clock to work with your DDR2-667 memory. If you install DDR2-800, keep it at 4:3 to generate a 400Mhz clock. Test this for a while to make sure that everything is kosher. Running Prime95 for an hour should be good enough, I wouldn't expect it to have any troubles but it's good practice to test each component incrementally.

Second, bump the CPU frequency from 8 to 9. This will increase the CPU frequency from 2.66Ghz to 3.00Ghz. Repeat the Prime95 test for two hours minimum. Keep an eye on your temperatures. If the system crashes, increase the CPU voltage by 0.05 volts and repeat.

Third, if it's stable and temperatures are acceptable (under 75 degrees for Prime95) increase the multiplier from 9 to 10 and repeat the stability test. If it seems stable at a 10x multiplier, run Prime95 overnight for 8 hours minimum.

 

[Openupitsdave]

Cool..I will definitely do it in stages using Prime95 like you said.. Thats awesome info...Now I just have to figure out how to adjust my FBS...so I started a thread over in the OCing forum since that would be going off topic a bit... http://www.tomshardware.com/answers/id-2155286/core2quad-66ghz-safely.html

Thanks a bunch bro!

 

[Pinhedd]

Cool..I will definitely do it in stages using Prime95 like you said.. Thats awesome info...Now I just have to figure out how to adjust my FBS...so I started a thread over in the OCing forum since that would be going off topic a bit... http://www.tomshardware.com/answers/id-2155286/core2quad-66ghz-safely.html

Thanks a bunch bro!

Yeah I saw that thread, you'll definitely get some help in the OC forum. It's a very, very bad idea to alter the FSB frequency through software while the PC is running. This can and often will cause crashes like that which you experienced. Always do it from within the system setup, as this will only take effect when the PC is restarted. This allows for the clock generator and all synchronized devices to be fully reinitialized without corrupting the state of the logic.

 

[Openupitsdave]

I had a bad feeling since the second I downloaded it... I hope I didnt corrupt anything... CPU-Z says my FBS is back at 266 and all my numbers seem to line up...hopefully its all good on the inside though :/

Your'e the man pinhedd.

 

[Pinhedd]

I had a bad feeling since the second I downloaded it... I hope I didnt corrupt anything... CPU-Z says my FBS is back at 266 and all my numbers seem to line up...hopefully its all good on the inside though :/

Your'e the man pinhedd.

thanks