Opteron and FX chips

[geeza]

Is the Opteron 146 basically the same as an underclocked FX57 thats down from 2.6ghz to 2ghz?

If so what so good about the FX57 that makes it £476 more expensive? (apart from the name of course)

 

[Havana_UK]

All the Opteron UPs, and all 1MB cache A64s are basically the same as the FX57. They all use the same San Diego core.

The main difference of the FX series is that they have unlocked multipliers, which makes them great for overclocking.

AMD justify the high price because:
- they are hand picked for stable high-speed operation
- a relatively low part of the yield makes the grade

Opterons are also hand picked, but in their case hand picked for low voltage operation (which means low heat, which means easier passive cooling; important in the server / workstation market).

The FX range are premium processors, which always carry a higher price tag. If you graphed the price against the performance right across the A64 range, you'd see an exponential curve. That's just the way things are.

Finally, to get the most out of an Opteron you need a board capable of stable high HTT (290+), which is not a requirement with an FX processor due to easy o/c'ing by increasing the multi.

Hav

 

[geeza]

All the Opteron UPs, and all 1MB cache A64s are basically the same as the FX57. They all use the same San Diego core.

The main difference of the FX series is that they have unlocked multipliers, which makes them great for overclocking.

AMD justify the high price because:
- they are hand picked for stable high-speed operation
- a relatively low part of the yield makes the grade

Opterons are also hand picked, but in their case hand picked for low voltage operation (which means low heat, which means easier passive cooling; important in the server / workstation market).

The FX range are premium processors, which always carry a higher price tag. If you graphed the price against the performance right across the A64 range, you'd see an exponential curve. That's just the way things are.

Finally, to get the most out of an Opteron you need a board capable of stable high HTT (290+), which is not a requirement with an FX processor due to easy o/c'ing by increasing the multi.

Hav

doesnt a divider sort of work in the same way as an unlocked multiplier. Otherwise my opteron will be stuck at 10x which would mean if my memory didnt go about 200mhz it wouldnt overclock at all?

 

[Kyo]

That only if your running on 1:1 basis

Divider is normally associated to the Memory and not the actual CPU multiplier. What that allows is the CPU to run at higher speeds while keeping your memory clocked at base or less if needed.

 

[geeza]

That only if your running on 1:1 basis

What that allows is the CPU to run at higher speeds while keeping your memory clocked at base or less if needed.

so is that like a multiplier that does not effect the memory. i.e a CPU only multiplier?

how does the devider work basically

i know that

multi = 10
fsb = 200
=200*10 so 2000mhz
where does the divider play a part as i never used one on my NF7 board

 

[Havana_UK]

Multipliers work by multiplying up the HTT (FSB) to generate the internal clock frequency of the CPU.

In the A64 system there are actually two multipliers. A CPU multiplier, and the HT multiplier (called something else I can't recall right now), which generates the frequency for the HyperTransport bus.

FX57 for example as standard is a x14 multi (200 x 14 = 2800MHz), however it can be overclocked by simply raising the multiplier, e.g. to x16 resulting in a 400MHz o/c (200 x 16 = 3200MHz).

Overclocking in this way doesn't stress the RAM, or the motherboard (unless you need to up the volts) - only the CPU. This is where FX's come into their own - because they are hand picked, literally the best of the best, they generally have a lot of potential when it comes to overclocking.

If you wanted to overclock say a 3700+ (2200MHz standard, 200 x 11), then the only way to do so is by raising the HTT (or FSB in Intel / A-XP speak), since you can't increase the multi above x11. This places additional stress on numerous other components including the RAM & the Northbridge chipset.

This is where dividers are most useful, because you can increase the HTT speed up to 250MHz, giving a CPU speed of 2750MHz (250 x 11) but keep your RAM close to 200MHz by using say a 166MHz divider (166MHz / 200MHz = 0.83, 0.83 x 250MHz = 207MHz), or a 133MHz divider (133 / 200 = 0.66, 0.66 x 250MHz = 166MHz).

Dividers weren't that useful before the days of A64, because they limited the performance of Athlon XP systems pretty severely. A64 performance, conversly, doesn't really suffer from running the RAM on a divider.

Hope this helps.

Hav

 

[Kyo]

so is that like a multiplier that does not effect the memory. i.e a CPU only multiplier?

how does the devider work basically

i know that

multi = 10
fsb = 200
=200*10 so 2000mhz
where does the divider play a part as i never used one on my NF7 board

Ok - it took me quite a bit of reading and research before it made some sense but the A64 architecture basically is the same but with some additonal flavours.

All you really need to worry about is this

CPU clock = FSB x CPU Multi = ie 200 * 10 = 2000Mhz

HTT speed = FSB x HTT multi = ie 200 * 5 = 1000Mhz * 2 (ddr) = 2000 HTT speed which is correct. All u need to remember here is that for a 939 socket the HTT total clock should NOT exceed 2000 so as a lot of peeps have suggested you should drop the HTT multi if your going higher fsb.

Now this is where the divider comes in if you are running ie 200 1:1 that means basically FSB = Memory Speed. Which will be ok if you have decent memory that can handle more then 200.

A divider basically allows you to still up FSB so that your clock speed will overclock but still allow the memory to run at whatever your max speed your memory can run to.

If you have lower quaility memory that can handle up to 200 but nothing beyond that then a divider will fundemantally run it at 200 which in affect will yield overall ower memory bandwidth. Which shouldn't necessary give you a poorer performance from your rig.

 

[Havana_UK]

Beat you to it by 4 minutes Kyo!

Couple of points as well.

HTT & HT are different things. HTT is FSB, and HT is the HyperTransport bus which operates at 1GHz, so...

CPU clock = HTT x CPU Multi
HT clock = HTT x HT Multi

Hav

 

[geeza]

thanks. If I wanted to keep my ram from dieing/slowly dieing on me what sort of settings would I be looking for?

ram is 2gb geil value, processor 146, motherboard DFI ultra-D

why dont amd just make it so all processors are multiplier unlocked? it would make it far easier for everyone else. (but their pockets would be lighter im suspecting)

 

[Havana_UK]

thanks. If I wanted to keep my ram from dieing/slowly dieing on me what sort of settings would I be looking for?

ram is 2gb geil value, processor 146, motherboard DFI ultra-D

Basically you should be looking to keep your RAM at or close to 200MHz. Despite being 'value' RAM, I've found all the GeIL stuff to be excellent. I use the 2GB set in my 2nd PC, and run it at 2.5-3-3-7 1T @ 210MHz @ 2.7V.

why dont amd just make it so all processors are multiplier unlocked?

Question.

it would make it far easier for everyone else. (but their pockets would be lighter im suspecting)

Answer.


Hav

 

[geeza]

doesnt the pencil trick work like it did with the thunderbirds or are they slightly mroe advanced now?

 

[Havana_UK]

Nope, cache is now disabled on the die itself, and all of them use the 1GHz HyperTransport bus.

Hav

 

[GAMEfreak]

what about these dual cores which are being sold as single cores with one core disabled? any chance of these being unlocked? and does each core of a dual core cpu HAVE to work at the same clock speed?

 

[Havana_UK]

Not heard about that TBH, so no idea.

To my knowledge, both cores must run at the same speed, since they don't have independent clock sources.

Cheers,
Hav