Info on Over Clocking!

[gate1975mlm]

I am new to over clocking! I may get a AMD Athlon 64 3500+ 939 512+ 90nm Chip And OCZ EL Platinum Revision 2 Dual Channel memory!

If I over clock the CPU will I also need to over clock the memory? And What could I over clock them to without any damage? And Would I need to add lots of cooling?

Thanks

[mustrum]

I am new to over clocking! I may get a AMD Athlon 64 3500+ 939 512+ 90nm Chip And OCZ EL Platinum Revision 2 Dual Channel memory!

If I over clock the CPU will I also need to over clock the memory? And What could I over clock them to without any damage? And Would I need to add lots of cooling?

Thanks
You can set a divider so the memory wont get OCed while you OC the CPU.
With the MSI K8N Neo2 you just set the memory from 200mhz to 166 or 133 mhz to use those dividers. Dunno about other motherboards.

[saturnotaku]

I am new to over clocking! I may get a AMD Athlon 64 3500+ 939 512+ 90nm Chip And OCZ EL Platinum Revision 2 Dual Channel memory!

If I over clock the CPU will I also need to over clock the memory? And What could I over clock them to without any damage? And Would I need to add lots of cooling?

Thanks

There's no blood coming out of this stone! This topic has been discussed to death in this and just about every forum imaginable. Take a few hours to search through here and the forums at amdmb.com, use (google) to read reviews and search for guides on overclocking. Come back with what you learn and if you have any further questions. You can learn a lot by simply taking the time to educate yourself rather than have everything spoon fed to you.

And as long as you're reading this, please click on the "posting and you" link located in my signature and watch the Flash animation contained therein.

[CaptNKILL]

Since everyone asks, maybe you should sticky one of the Athlon 64 overclocking threads :rolleyes:

[DiscipleDOC]

Hey Capt,
I know it's off topic, but do you have your vid card water cooled.....

[john19055]

It may have been discuss to death but I still have'nt found one that explains how it all works I mean the whole HTT stuff ,is when I set the HTT to 3x does that mean my cpu is running with a 166mhz divider and my memory is still running at 200mhz when I have the memory set at 200mhz Like if I have the multipler set at 12 and the HTT set at 3x does that give me a speed of 1.992g for the CPU and the memory running at 200mhz would the speed of my memory be 2.4g or would setting the HTT to 3x automantically set my memory at 166mhz. ,I have a A64 3400+ 754 socket and it is confuseing me how all this works.I had the XP's figured out but I have'nt figured out just how the A64 work yet.

[CaptNKILL]

Hey Capt,
I know it's off topic, but do you have your vid card water cooled.....
Nope, stock cooling. And its the original single fan cooler too.

I love this card :D

I have lowered my clocks to 409\1120 since I got HL2 though. I was getting some flickering pixels in some areas. It emediately went away when i lowered them.

[CaptNKILL]

It may have been discuss to death but I still have'nt found one that explains how it all works I mean the whole HTT stuff ,is when I set the HTT to 3x does that mean my cpu is running with a 166mhz divider and my memory is still running at 200mhz when I have the memory set at 200mhz Like if I have the multipler set at 12 and the HTT set at 3x does that give me a speed of 1.992g for the CPU and the memory running at 200mhz would the speed of my memory be 2.4g or would setting the HTT to 3x automantically set my memory at 166mhz. ,I have a A64 3400+ 754 socket and it is confuseing me how all this works.I had the XP's figured out but I have'nt figured out just how the A64 work yet.
Read this guide:
http://www.insanetek.com/index.php?page=overclocka64

Its very very informative :)

[OCForums_Osirus]

Since no one would actully give you the infomation you wanted, here you go
Credits - hitchjb1 @ OCforums.com

Overclocking setting for various bus frequencies

In A64 system, there is no external FSB per se, there are the CPU, the memory bus, the HT bus. The FSB becomes an internal bus (or setting) of the CPU. The term FSB still exists in motherboard bios to set various frequencies.

Some bios, CPUID utilities call FSB as HTT or internal bus, so FSB is used interchangeably with HTT as a setting to set CPU frequency, memory bus frequency, HT bus frequency until everybody agree and use the same terms.

HT bus or HyperTransport bus is not the same as HTT (see 3 below).

1. CPU_frequency = FSB x CPU_multiplier

CPU mulitplier is CPU specific, some can be adjusted from below up to the stock multiplier of the CPU.
E.g. A64 754 3200+, stock 2GHz = 200x10, multiplier X10, X9, X8, X7, ....

CPU multiplier

The FX are unlocked.

But the A64 754 are unlocked up to the default stock multiplier.
E.g. for a A64 754 3200+, 2 GHz stock frequency, default multiplier is x10, so it is unlocked for x10, x9, x8, ....
This is good since one can still overclocking the FSB which is related to the HT bus, memory bus via their respective multipliers.


2. AGP_frequency

Can be set independently if motherboard/chipset have PCI/AGP lock such as w/ chipset Nforce3 250 GB. K8T800 Pro may still have PCI/AGP lock problem.
E.g. AGP can be adjusted to hold constant at 66, 67, 68, ... MHz independent of the FSB overclocking.


3. HT_bus_frequency = FSB x HT_multiplier

HT_multiplier (also called LDT multiplier), most bios has it ranged between 1X and 5X.
E.g. FSB = 200 MHz, 1X to 5X for HT from 200 MHz to 1000 MHz


4. memory_bus_frequency = FSB x memory_FSB_ratio

In terms of CPU_frequency
memory_bus_frequency = CPU_frequency / CPU_memory_divider
or
memory_bus_frequency = CPU_multiplier x FSB / CPU_memory_divider
where
CPU_memory_divider = ceiling(CPU_multiplier / memory_FSB_ratio)

Using this formula, the CPU_memory_divider can be calculated based on CPU_multiplier and memory_FSB_ratio.
Some common cpu_memory_dividers generated by spreadsheet are listed in this table.
Relationship between CPU_memory_divider and CPU_multiplier, memory_FSB_ratio
How to determine memory bus frequency
From which the memory bus frequency can be determined
(memory_bus_frequency = CPU_multiplier x FSB / CPU_memory_divider).

Some planning/estimation based on the CPU multiplier, memory rating to ensure the CPU_memory_divider is an integer. Otherwise some round down of memory bus speed would occur as the divider would round up to next integer.

E.g,
HTT = 270 MHz
CPU_multiplier = 9
memory_FSB_ratio = 5/6 (= 166/200 bios setting)
So
CPU_frequency = 270 x 9 = 2430 MHz
CPU_memory_divider = ceiling(9/(5/6)) = 11 or from table in link
memory_bus_frequency = 2430 /11 = 221 MHz
HT_bus_frequency = 270 x 3 = 810 MHz (using x4 would be to high)
AGP/PCI is locked (AGP = 66, 67 MHz)

- Additional settings are the RAS/CAS timings of tRAS, tRCD, tRP, CAS.
- Can run any speed (ASYNC) using the CPU_memory_divider, to match memory module speed.
- Slow or faster memory can be used to get whatever bandwidth allowed in the memory modules.
- ASYNC has minimum impact on memory bandwidth efficiency
- 754 efficiency 95%+, 939 efficiency 86%+

For desirable overclocking control, one should be able to set all these frequencies of CPU, HT, AGP/PCI, memory independently as shown above. Exact bios naming may vary.


Appendix: Memory SYNC vs ASYNC

SYNC: FSB = memory_bus_frequency (or memory_FSB_ratio = 1/1)

Without a higher ratio of memory_FSB_ratio > 1, running SYNC is the easiest way to max out a memory module that can take high bus frequency.
E.g. with PC4000 or above, by running the FSB (HTT) as high as possible, to 250 - 300+ MHz. Many boards are able to support 300 MHz FSB (HTT) stable.

If HT bus is limited to around 1000 MHz,
- when FSB (HTT) at 250 MHz, HTT_multiplier can be set at x4,
- when FSB (HTT) is far beyond 250 MHz towards 300 MHz, HTT_multiplier may have to be dropped to x3 so the HT bus is stable under 1000 MHz.
This is a tradeoff between memory bus frequency and the HT bus frequency.

E.g. assume CPU maxed around 2500 MHz, with PC4000-4400 memory
Case 1 (PC4000):
FSB = 250 MHz, CPU_multiplier = 10, CPU_frequency = 2500 MHz
HT_bus_frequency = 1000 MHz (w/ x4 HT_mulltiplier)
CPU_memory_divider = 10/1 = 10
memory_bus_frequency = 250 MHz
Case 2 (~PC4400):
FSB = 280 MHz, CPU_multiplier = 9, CPU_frequency = 2520 MHz
HT_bus_frequency = 840 MHz (w/ x3 HT_mulltiplier)
CPU_memory_divider = 9/1 = 9
memory_bus_frequency = 280 MHz

ASYNC: In general, FSB != memory_bus_frequency.

memory_bus_frequency = FSB x memory_FSB_ratio
where memory_FSB_ratio = ..., 6/5, 5/4, 4/3, 3/2, 2/1, 1/2, 2/3, 3/4, 4/5, 5/6, ...
In some bios, only a few can be selected.
- FSB = 200, memory = 200, memory_FSB_ratio = 1/1
- FSB = 200, memory = 166, memory_FSB_ratio = 5/6
- FSB = 200, memory = 160, memory_FSB_ratio = 4/5
- FSB = 200, memory = 150, memory_FSB_ratio = 3/4
- FSB = 200, memory = 133, memory_FSB_ratio = 2/3
- FSB = 200, memory = 100, memory_FSB_ratio = 1/2

E.g. assume CPU maxed at around 2500 MHz
Case 1 (CPU x10 max, ~ PC3200):
FSB = 250 MHz, CPU_multiplier = 10, CPU_frequency = 2500 MHz
memory_FSB_ratio = 5/6
CPU_memory_divider = 10/(5/6) = 12
memory_bus_frequency = 208 MHz
Case 2 (CPU x9 max, ~ PC3200):
FSB = 280 MHz, CPU_multiplier = 9, CPU_frequency = 2520 MHz
memory_FSB_ratio = 3/4
CPU_memory_divider = 9/(3/4) = 12
memory_bus_frequency = 210 MHz
Case 3 (CPU x8 max, ~ PC4000):
FSB = 310 MHz, CPU_multiplier = 8, CPU_frequency = 2480 MHz
memory_FSB_ratio = 4/5 (may not be available, may need 3/4 or 5/6)
CPU_memory_divider = 8/(4/5) = 10
memory_bus_frequency = 248 MHz (assuming 4/5 ratio)

[DiscipleDOC]

Good info, Osirus.

[MUYA]

Note: Seriously gate1975mlm, one more thread start by you asking questions a) you have asked before, or b) you can find in the forums thru searching. YOU WILL BE BANNED. ENOUGH IS ENOUGH.

[Woodelf]

Nice job OCForums_Osirus !!.

[OCForums_Osirus]

Thank you!

[DiscipleDOC]

Hey! I said it first! (mikec)

[Woodelf]

Hey! I said it first! (mikec)
Nice job, DiscipleDOC !! (xmasgrin)

[gate1975mlm]

thanks