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Setup Recommendations for IBM PC 300 | 6345

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wdobry

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Sep 22, 2023
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Hello everyone,

I've recently acquired a mint-condition IBM PC 300 (6345) from June 2000. Today, I took the plunge and unboxed it, giving it its first-ever start. After replacing the CMOS battery, everything worked right out of the box.

The computer comes with a Celeron 500Mhz, 5GB HDD, and 32MB SDRAM. It's a relatively basic setup for this model. Additionally, I have a VooDoo 3 2000 PCI that I plan to install soon.

I have a few questions and am seeking recommendations for potential upgrades:

CPU:
Based on the manual, it lists the following processors for this model:
  • Socket 370 with a detachable CPU heat sink and fan.
  • Supported processors:
    • Intel Celeron 533 MHZ
    • Intel Celeron 500 MHZ
    • Intel Celeron 600 MHZ
    • Intel PIII 550 MHZ
    • Intel PIII 600 MHZ
    • Intel PIII 667 MHZ
However, there's some discrepancy as I've come across information on IBM's website suggesting these machines could support Pentium III processors up to 800mhz. Can anyone clarify if the PIII 667 MHZ CPU is the maximum this PC can handle? Would love any recommendations for a specific model here.

RAM:
Is it possible to upgrade this PC with two 168-pin SDRAM DIMMs, each of 256MB, making a total of 512MB? The manual mentions 512MB maximum capacity, but this website suggests that it's 256MB.

Sound Card:
I'm in a bit of a bind here. I'd like to know which sound card from 1999 or 2000 would offer the best performance for this system.

CD-ROM Drive:
I'm trying to understand the CD-ROM drive specifications from the manual:
  • 5.25-in., 40X CD-ROM IDE/AT drive.
  • It can read data and play audio from both standard and mini CD-ROMs as well as audio CDs.
Does this mean the PC can only support a maximum 40x speed drive? Apologies if this seems like a basic question, but I want to ensure I make the right purchases. Any recommendations for a suitable CD-ROM drive would be greatly appreciated.

Thank you for your assistance!
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Last edited:
wdobry said:
CD-ROM Drive:
I'm trying to understand the CD-ROM drive specifications from the manual:
  • 5.25-in., 40X CD-ROM IDE/AT drive.
  • It can read data and play audio from both standard and mini CD-ROMs as well as audio CDs.
Does this mean the PC can only support a maximum 40x speed drive? Apologies if this seems like a basic question, but I want to ensure I make the right purchases. Any recommendations for a suitable CD-ROM drive would be greatly appreciated.

Thank you for your assistance!
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Click to expand...

Pretty sure that means that the machine originally shipped with a 40x drive. Any speed IDE drive will work.
 
Here is the manual for your machine.


I can't find any information on the fastest CPU it will support, just the manual stating 667 MHz. You can always try playing the CPU lottery and see if you get lucky and find a higher clocked part that works. Just remember, you're almost certainly limited to Coppermine only Pentium IIIs, since the Tualatins used a different bus protocol and different core voltage. If you can find a BIOS update for your board, it may add support for additional CPU models.

As for the memory, 512 MB is the maximum. The IBM manual doesn't list the chipset, but it's most likely an i810 or i815, which have a hard 512 MB memory set in the chipset. The i8xx desktop chipsets were part of their new market segmentation strategy, they didn't want desktop boards eating into their new Xeons' lucrative sales. They learned from their "mistake" with the 440BX chipset, of giving pleb desktop users lots of value for their money, they'd never make such a feature rich chipset for the desktop market ever again.
 
Update:
RAM maxed out and upgraded to 512MB :)
CD-ROM Drive installed and works nicely

@GiGaBiTe Thank you! I've also did some digging since I've posted this thread.

This is the motherboard on this machine:
https://theretroweb.com/motherboards/s/gigabyte-ga-6wmmc7-e1

I've purchased few used CPUs (667 MHz, 800 MHz, and 1000 MHz) but I have high hopes for this one:
https://www.cpu-world.com/sspec/SL/SL5B3.html

New questions:
Can't figure out maximum capacity for the HDD and I don't have any of them laying around to test if I'm on 8.4 GB limit or 32 GB.
 
By the time your machine came out, it was well past the 32 GB limit. The next drive size limit was caused by 28 bit LBA, which limited drive sizes to 137 GB. The 8.4 and 32 GB limits were several years earlier in the 1996-1998 time frame.

YMMV if you have that limit or not. Most of my late PIII systems from 2000-2003 support 48 bit LBA and have no real drive size limitation, instead it becomes a software support issue. Windows 98SE/ME only support 28 bit LBA and have a 137 GB partition limit. There is a patch available, but you have to ask yourself "is it worth having such a huge partition on an OS that is highly unstable with a file system (FAT32) that is not at all fault tolerant?" On a cooperatively multitasked OS with a not at all fault tolerant file system, any little thing that goes wrong can potentially end up in massive data corruption that only gets worse the larger the hard drive is. And since Scan Disk and Disk Defragmenter were never designed for such huge partitions, you'll be having some all night cookouts when something implodes on itself. You can backport the system tools from ME to 98 to gain a bit of speed, but not much.

Windows 2000 also has the 28 bit LBA limit, until SP4 was released, and even then you needed to do some registry tweaks. While Windows 2000 was a bulletproof OS for the time, it can be a major headache getting a large partition formatted for it, especially since setup didn't offer a quick format option. This forced you to use a 3rd party disk management utility like Seagate's Disk Wizard.

If the retro web is accurate and you have an i810E chipset, it does support 133 MHz FSB CPUs, so you may get away with a 1 GHz part, if the BIOS has support for it. That's the fastest generally available Coppermine part. There is a 1100 MHz and a very rare 1133 MHz part, but the additional 133 MHz isn't going to net you much extra performance, especially on a board with no AGP slot.
 
@GiGaBiTe I've played with two CPU's (667, and 1000), although at startup I'm getting a BIOS message:
162 No Processor bios update found.
Click to expand...
What is weird is that the processor is fully recognised in BIOS, and if I skip (exit) the Setup process the Windows starts normally, and seems to be working just fine.
I'm wondering if there is anything I can do besides updating the BIOS. I never did that on old PC and I'd like to avoid it if possible.Screenshot 2023-10-07 at 19.25 1.pngScreenshot 2023-10-07 at 19.25 2.png
 
That error unfortunately means that the BIOS image doesn't have microcode support for the 667 and 1000 MHz part. Just because the BIOS can correctly detect the core clock and processor type, doesn't indicate support for it.

Without correct microcode support for the CPU, you may encounter strange behavior in operating systems and software. Some features may be broken (most commonly ACPI support) and some bugs that may be present on that mask revision may be unpatched. The only way you'll find out is by running the machine with that CPU and see if it's stable or not. I'm assuming that CPU error comes up on every boot, so you'll have to deal with that as well. The Pentium 3 didn't introduce any major changes during its lifetime, so you shouldn't have to worry about missing instruction support.

You are correct in wanting to avoid doing BIOS flashes on that machine, it is a very risky endeavor. A lot of things can go wrong outside of your control, like glitches or memory errors causing the programming software to lock up mid-flash and brick the system, or write incorrect data to the flash chip. The flash chip could also have stuck bits and fail to flash properly, or have weak bits that get corrupted during flashing.

I wouldn't recommend having an EEPROM programmer on hand before attempting to do a BIOS flash. You'd be able to dump the image currently on the motherboard and back it up, which is something I'd recommend doing anway, bitrot is a real problem.
 
Thank you @GiGaBiTe

Here is an update of the original post:
I was wrong about the motherboard on this unit. I've did some more digging and I'm sure now that this is the correct motherboard: Gigabyte GA-6WMMC7 (OEM) It seems it's only good for CPUs at 100Mhz FSB.

On Gigabyte website I've found two pages with documentation, but none of them with the correct rev.
GA-6WMM7 (rev. 2.0) , GA-6ZMM7

I also went through possible bios updates, and I'm trying to evaluate if it's worth trying to update it. There is some additional CPU support added in the latest version I could find: http://ps-2.kev009.com/pccbbs/netvista/ptjt20a.txt but it doesn't explicitly say which CPUs are supported.

I've purchased this CPU: https://www.cpu-world.com/sspec/SL/SL5QW.html which I think has the highest chance of working without touching BIOS.

I'll update this post after testing more CPUs. Thank you.
 
You're not correct in assuming the board only supports 100 MHz FSB CPUs. The fact that the PIII 1000 works, and at the correct speed means it does. It only lacks the microcode for it. If your motherboard didn't support a 133 MHz bus, the system either would have not booted at all, or would have booted at a lower speed (750 MHz). The former likely would have happened, because Intel by this time was getting very rigid with their desktop chipsets.

If you're also getting the error with the slower 667 MHz part, and the manual explicitly says it supports it, probably means you have an older BIOS revision that existed prior to the manual being written, and the manual was updated at some point during the product's lifecycle to add newer CPUs to the support list. The fact that it lists the 667 MHz part explicitly states it supports 133 MHz FSB, because that's what the 667 MHz part uses.

You have to remember that CPU clock speeds in that era were advancing at a lightning pace. From October 1999 to July 2000, the Pentium 3 went from 500 MHz to 1.13 GHz. Manufacturers were having a hard time keeping up with the pace of CPU development and had to rapid fire BIOS releases to keep adding support for newer parts. There were so many CPU models at one point that motherboard manufacturers sometimes had to make multiple BIOS images that supported different groups of processors. I remember a few TYAN motherboards that had that problem. AMD had a similar problem decades later on AM4.
 
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