Overclocking the Phase 5 CSPPC

and

CS MK III boards


Overview.

The Cyberstorm PPC is a dual processor PPC604e / 68060 card clocked at 200 MHz and 50 MHz respectively, although there are other variants using different speeds. The Cyberstorm MKIII is identical, though without the PPC chip and associated circuitry. MKIII users can therefore, ignore any references to the PPC in this discussion. The MKI and MKII versions of the Cyberstorm are different and the information here does not apply to them. Note that I cannot guarantee the accuracy of this information, nor can I accept any responsibility if you damage yourself or your hardware. Make sure you fully understand what you are doing before you atttempt to overclock this board. Overclocking will also void your warranty, so don't ruin your board and expect it to be replaced for free! Also bear in mind that the results I have obtained here may vary with what you may obtain on your system. Use these figures as a guide only. these figures as a guide only.

My overclocked card has been running at 225 MHz for the PPC and 66 MHz for the 060 for over 2.5 years with no problems in my tower-cased A4000. Desktop A4000 users will need to pay extra attention to cooling. I did have a few reliability problems earlier, which was traced to poor contact with the 200 pin CPU connector. This was caused by the board being mounted vertically in my tower case. Desktop users may not have this problem as their boards are mounted horizontally, and gravity may help hold it in place. I cured this problem by removing the original nylon clip-on type standoffs and fitting threaded standoffs of the appropriate size. The card was then fixed firmly in place with four screws.

The PPC board can use up to 3 separate clock oscillators to provide timing for the CPUs and system devices. System devices include the onboard SCSI controller, the interface to the CVPPC video card and some Amiga motherboard timing. The clock oscillators can be seen in the photo at the top of the page, numbered 1 to 2. Note that position 3 is empty in this picture. These oscillators come in several forms, and again, in the picture, No 1 is in a plastic case and No 2 is in a metal case. Both types are completely interchangeable, assuming they are of the same frequency. Note that pin 1 on each of these is indicated by a dot or notch on the packaging, and if these oscillators are changed, the new one must be given the same orientation as the old. Pin 1 is to the top right in the picture.

PPC clock.

The first clock signal is used to clock the PPC chip, and as such, is not used on the MK III board. This by default is generated in oscillator No 1, to the right in the picture. Normally it is a 66.666MHz oscillator, which is multiplied by 3 to give 200MHz. In the case of the 233MHz PPC, it is multiplied by 3.5 to give 233MHz. This multiplication ratio can be changed by a set of jumpers (see below). To overclock the PPC chip, you can either change the oscillator or change the multiplier ratio. For a 200MHz PPC, I found a 75MHz oscillator to work best, giving a resultant PPC speed of 225MHz. Otherwise, the original 66MHz oscillator can be retained and the multiplier ratio increased from 3X to 3.5X, giving a PPC speed of 233MHz. Of the two methods, changing the oscillator gave the best overall results. This is because the RAM access is also sped up. Changing the multiplier only speeds up part of the PPC chip itself, and the only times you gain more performance over the oscillator swap method is when the program being executed can fit entirely within the PPC's cache. So if you like running lots of MPEGs, change the oscillator. If you like running small programs like benchmarks or the RC5 client, change the jumper. When overclocking, do not use anything higher than 75MHz or increase the multiplier by more than one step. Also do not do both together. It won't work!

System clocks.

The other two clock signals are usually generated together in a single oscillator. For clarity, I'll describe them separately. The system devices are driven from oscillator No 2, which is in the centre. This is a 50MHz oscillator, and it's signal is divided by 2 to derive 25MHz clocks for the SCSI controller and for the Amiga motherboard. The modified PCI interface for the CVPPC also gets it's timing from this clock. After much experimentation, I found a value of 60MHz to be the best, giving a worthwhile speedup to the interface for the CVPPC while still maintaining full reliability for SCSI and motherboard devices. Benchmark values for the CVPPC can be found below. The CVPPC itself can also be overclocked.

68060 clock.

The third clock signal is used to drive the 68060 (or 68040). Normally it is also derived from oscillator No 2 in the centre, however, by changing jumpers (see below) it is possible to assign this to the 3rd oscillator position on the left. By then fitting an appropriate oscillator, the user can then overclock the CPU separately from other devices. This means that the 68060 can be overclocked further than the 60MHz allowed by oscillator No 2. I have tested both 50MHz and 60MHz 68060s. The 50MHz version gave a maximum of 65MHz and the 60 gave a maximum of 67MHz. It seems that once the user exceeds about 67MHz, it appears that RAM speed becomes a limiting factor as I found that by switching the waitstates to 70nS by use of the boot menu, I was able to obtain partially reliable operation at 70MHz. There is also another, more serious problem if the 060 is clocked using the 3rd oscillator. Some PPC programs will hang after running a while (eg ISIS PPC or Frogger). This will limit you to overclocking with the centre oscillator only, unless a switch is provided to switch oscillators for the times these particular programs are used (see below). You then have the choice of 60MHz for reliability or 66MHz for speed. In later versions of the CSPPC, Phase 5 had rearranged the RAM circuitry in order to allow the use of 60MHz 060s. These boards have slightly slower memory access compared to the earlier version and it is also possible to change the RAM precharge settings in the boot menu, unlike the earlier versions of the CSPPC (such as mine), where the precharge buttons were always ghosted out. Users of the newer boards can overclock their 060 further - up to 73MHz according to one report. This version of the CSPPC also does not have the problems caused by clocking the 060 separately and users of these newer boards can simply move the jumper and fit a faster oscillator without need of switches. Note that as far as I know, these two versions of the CSPPC look physically identical.

Cooling.

Of course as you know, overclocking means that the board will run hotter. You will need to perform the following modifications in order to keep the board cool. Fit a heatsink to the 68060. I used a "bed of nails" heatsink taken from an old A3640 board. It works very well. The Permedia 2 chip (if you have a CVPPC) will also now need extra cooling. I used a finned TO220 style transistor heatsink glued on top of this chip. Try your local electronics parts store for this item. If you can't find the correct type of heatsink glue, you could use superglue, though it may weaken from the heat after a while. The PPC chip does not need any extra cooling, though make sure it's heatsink and fan are working OK. Finally add a small fan taken from a PC CPU heatsink/fan unit, and position it as shown in the picture above so that it blows air down along the top two SIMMs. This keeps the PAL chips under those SIMMs cool, and helps keep cool air circulating across the entire board. If you have a desktop case which lacks the required room, look here for details on how to fit this fan. Also I recommend doing the other mods outlined there to improve cooling further. The best way to test both overclocking reliability and cooling is to get both the PPC and 68K RC5 clients from Aminet and run them together for several hours. Your system should not overheat or have unexplained crashes during this time.


Jumper Settings:

There are three different sections utilising jumpers. They are PPC division ratio, found under the PPC heatsink; general system timing, found on the edge of the PCB, near the SIMMs; and the 68K voltage selector, found inside the 68K socket (remove the 68K chip to reveal it). Be VERY CAREFUL when changing these jumpers. They are TINY surface mount jumpers, which look like surface mount resistors, and both the jumpers and the PCB tracks can be very easily damaged. Get a qualified electronics technician to change them. Note that they are completely unlike the standard pin type jumpers which use removable shorting blocks.

PPC clock multiplier jumpers.

These jumpers are located beneath the PPC chip's heatsink, which is attached to the PCB by two spring clips. With the PCB oriented as in the picture at the top of the page, the jumpers are located to the top left of the PPC chip. Refer to the diagram below for the various multiplier ratios. For example, the leftmost one below is the default setting for a 200MHz PPC board, using a 66.666MHz oscillator in position 1. This is multiplied by 3 to give 200MHz. Changing the positions of the jumpers to reflect 3.5:1 will multiply the 66.666MHz clock by 3.5, giving a frequency of 233MHz.

System jumpers.

These jumpers are located to the right of the PCB, underneath the second from top SIMM. Below is a table of what they may do. Note that I obtained these results from experimentation, so I can't promise total accuracy. The jumper positions shown are for a standard 200MHz PPC, 50MHz 060 board. A clearer idea of their location can be found in the picture below, in the "How to overclock" section.

1:- Unknown - this jumper has no apparent effect.

2:- Unknown - this jumper has no apparent effect.

3:- Swaps PPC clock source from oscillator 1 (default) to oscillator 3 (alternative).

4:- Moves PPC clock source from oscillator 1 (default), adding to oscillator 2 (alternative), making it possible to clock both CPUs from oscillator 2.

5:- 68K processor select, 68060 (default), 68040 (alternative). See below for more details.

6:- 68K clock source, Oscillator 2 (default), oscillator 3 (alternative). System devices continue to be clocked from oscillator 2 when alternative is selected.

68K CPU power voltage jumper.

A jumper for selecting the supply voltage for the 68K chip is also provided on the PCB. This can be found by removing the 68K chip. It is located in the hollow centre section of the 68K socket. Like the other jumpers it is a surface mount link, soldered in place. Fortunately it is somewhat larger than the other jumpers, and it also has the settings marked on the PCB. The default position (for an 060 board) is 3.3 volts. The alternate position for an 040 board is 5 volts. Be careful - you must NEVER operate this board with a 68060 installed and the jumper set to 5 volts. You will destroy the 68060! On the other hand operating the board set to 3.3 volts with a 68040 installed will not cause damage....it just won't work.


How to overclock - step by step:

This step by step outline shows you how to overclock a 200 or 233MHz PPC card with 50MHz 060. The oscillator values I have quoted here are suggested values that should work for most people. You may need to experiment with different oscillators if you run into problems. If you only want to overclock the PPC, you only need to do either step 1a or 1b. If you want to overclock the 060 only, or you have a MKIII card, do all steps with the exception of 1a/1b. If you want the simplest possible modification for overclocking the 060, (limited to 60MHz), do step 2 only with or without step 1a/1b. If you have a newer version CSPPC, where it is possible to alter the RAM precharge settings (see above), you may skip step 4 if you wish.

1a: EITHER carefully remove the 66MHz oscillator (number 1) and replace it with a 75MHz oscillator.

1b: OR change the multiplier jumpers as per the illustration above. I advise only increasing it to the next step up. For example, x3 (200MHz) to x3.5 (233MHz).

2: Carefully remove the 50MHz oscillator (number 2) and replace it with a 60MHz oscillator.

3: Solder a 66MHz oscillator into the empty number 3 position. Users of recent version boards can try faster oscillators - up to 73MHz.

4: Using the utmost care, remove the bottom jumper (No 6) and fit a SPDT type switch, wire the common to the centre solder pad, with the 2 switch contacts going to the other two pads. The "turbo" switch in a standard tower case is ideal for this. You can then select 60 or 66MHz as appropriate, while the system is powered up. I used a small connector glued to the board, with fine wire-wrap wire running to the pads.

5: Add a heatsink to the 060.

6: Add a heatsink to the Permedia chip (if you have a CVPPC card).

7: Add a small fan positioned to blow air down between the SIMMs (particularly between the top and second SIMM). Refer to the picture at the top of this page.

8: Test thoroughly, using the PPC and 68K RC5 clients over several hours of continuous use.

Note the position of the system jumpers, on the right-hand side of the PCB.


PPC Benchmark results.

I did a few tests to see how effective the overclocking was. You can clearly see the effects of faster RAM access for the PPC, as well as overclocking of the CVPPC data bus. The tests, from left to right are: PPC heatsink temperature, taken with an ambient temperature of 20 deg C, RC5 benchmark, taken with the old PPC RC5 client in benchmark mode (note that there is now a new, faster RC5 client), and ISIS PPC, running an MPEG called "Mandtrip" which can be found on Aminet. There were no "hacks" running in the system during these tests. 060 results can be found in the various SysSpeed modules below. The top (200Mhz) line is the results before overclocking.

Multiplier=66x3 (200MHz):- Temp=47.5 deg C, RC5=648334 Kkey/sec, ISIS=53.76fps.

Multiplier=75x3 (225MHz):- Temp=48.9 deg C, RC5=729222 Kkey/sec, ISIS=57.53fps.

Multiplier=66x3.5 (233MHz):- Temp=50.0 deg C, RC5=755788 Kkey/sec, ISIS=56.69fps.

Results with System clock=60MHz (overclocked CVPPC interface)

Multiplier=66x3 (200MHz):- Temp=47.4 deg C, RC5=648357 Kkey/sec, ISIS=58.26fps.

Multiplier=75x3 (225MHz):- Temp=48.9 deg C, RC5=729228 Kkey/sec, ISIS=63.53fps.

Multiplier=66x3.5 (233MHz):- Temp=50.3 deg C, Rc5=754287 Kkey/sec, ISIS=61.91fps.

SysSpeed modules.

A4k_66x3_50_50 This module is from a standard, unoverclocked 200MHz PPC, System clocks at 50MHz, 060 at 50MHz.

A4k_66x3.5_50_50 PPC overclocked to 233MHz, by changing the jumpers. System clocks at 50MHz, 060 at 50MHz.

A4k_75x3_60_60 PPC overclocked to 225MHz, by changing oscillator 1 to 75MHz. System clocks at 60MHz, 060 clock at 60MHz.

A4k_75x3_60_66 PPC overclocked to 225MHz, by changing oscillator 1 to 75MHz. System clocks at 60MHz, 060 clock at 66MHz.


Upgrading an 040 to an 060:

Both the Cyberstorm PPC and the Cyberstorm MKIII boards allow the use of either a 68060 or a 68040 processor. Both processors are quite similar, with the exception that the 68060 runs on 3.3 volts instead of the 68040's 5 volts, and the 68040 uses a 2x clock signal instead of the 68060's 1x clock. The following outline shows how to upgrade a 25MHz 68040 board to a 50MHz 68060. Note that I have not actually tried this myself - I do not have an 040 chip!

1: Install the appropriate 68060 libraries. Copy both the 68060.library and the 68040dummy.library into SYS:LIBS. Delete (or remove) the existing 68040.library, then rename the 68040dummy.library to 68040.library. When finished, power down the Amiga.

2: Carefully remove the 68040 chip by gently levering it up with a small screwdriver. Avoid bending the pins.

3: Locate the voltage select jumper, in the centre of the 68040 socket. Move it to the 3.3 volt position by careful soldering. (see above).

4: Move Jumper No 5 (see above) to the 68060 default position.

5: Install the 68060 chip into the socket.


Problems and solutions:

* Do not use crystal sockets, as socket & oscillator will be too tall and will foul the top-most SIMM. (I suggest using sockets during the testing process, with only 2 SIMMS fitted - then when you are happy with the overclocking, remove the sockets & solder the oscillators in)

* Do not use tall oscillators for the same reason above.

* Pay attention to correct oscillator orientation. Getting it wrong will destroy the oscillator.

* Be very careful when removing the old oscillators, as some people have damaged the copper tracks on their board.

* If using sockets for testing, use quality machined pin types (with round pins) to avoid damaging the PCB.

* You will need a small fan blowing through the SIMMs to ensure effective cooling, ie one taken from a CPU cooler is sufficient.

* Make sure the 200 pin CPU connector to the motherboard is clean and in good condition and that the CSPPC is bolted in place (see text)

* Make sure you have good quality 60nS SIMMS and that their contacts are clean. Many CSPPC problems are caused by bad memory.

* Make sure you have the latest Flash ROM revision to ensure best SCSI reliability.

* Check your power supply and power wiring if you have unexplained crashes. Check for overheating contacts in the 5V DC supply, especially on the 6-pin connector between the power supply and the motherboard.

* Some PPC programs crash when the 060 is clocked separately to the system devices. I suggest using the "turbo" switch (outlined above) and have the 060 running at 60MHz while running these programs. This problem does not happen if you have a recent version CSPPC.

* If you have SCSI lockups, make sure that the decimal value of maxtransfer if divided by your blocksize gives an integer result. For example, if you are using the default value of 512 bytes for your blocksize, your maxtransfer value should be 0xfff000. Set this for all hard drives and partitions on your CSPPC SCSI controller. Note that these SCSI lockups can often freeze your entire system, with the SCSI light permanently on.

* If you have a 233Mhz PPC (or have overclocked to that frequency) there is a bug in the PPC chip, which can be patched with csppc233fix.lha from Aminet.


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Introduced 11th July 1998. Updated 9th July 2000. Version 5.2