600E 55U upgrade problems

[tfflivemb2]

OK, I just pulled this from my post in the upgrade sticky, so that I can figure out what is wrong:

For those that might be interested...I have been beating my head against a wall trying to figure out how to bypass the 127 error, after adding a PIII 500 to my 600E (2645-55U)

The instructions as posted in the upgrade sticky, indicate to change byte 20 from 02 to 0A. Well, it took my a while to figure out which byte was actually 20, and it turns out the the number at byte 20 in the 55U was NOT 02, it was actually 00. I simply changed it from 00 to the 0A and it worked just fine. I also disabled the L2 cache, by changing the corresponding byte from 80 to 81, which by the way is what helped me figure out where byte 20 was, as there was only one byte that was 80.

My only complaint is that I didn't realize that the PIII 500 was a SpeedStep Model, which means that it is only registering at 333MHz. Might switch back to the 400MHz processor, until I get my 750MHz SS CPU.

EDIT: Ok, maybe it isn't the CPU after all. I rec'd the 750MHz, and it is only registering as 397MHz (w/ SS it should read atleast 600Mhz). I think that my problem is that this is a 2645-55U, which had a completely different BIOS than most of the other 600Es.

Any thoughts from anyone?

[AlphaKilo470]

In the main easy setup screen, you can see the BIOS version. Is it different than on other 600Es?

I'm thinking that the problem is CPU architecture, the original 600E which is what you have had the original PII core and 512kb of half-speed off-die L2 cahce whereas the later 600E computers had the Dixon core Pentium IIs which featured 256kb or on-die L2 cache. I think the difference in the chips and the way they handle various things might be why your 600E doesn't seem to like newer CPUs. If I'm not mistaken, you told me you had either a 400 or a 366mhz PII, and if I'm not mistaken, the 400 and 366 came only as Dixon cores so why don't you see if you can at least get one of those working right, that could test my theory to an extent.

[tfflivemb2]

The 400Mhz that I have works flawlessly.

As for the BIOS, the BIOS version is different from the others. (See the BIOS file Matrix) The 55x and the A5x are different from the others. I have the latest BIOS for this system.

Latest BIOS for 55x and A5x:
IHET47WW (1.15)

Latest BIOS for other 600Es:
INET36WW (1.16)

Maybe it is a different architecture, from the newer 600Es.

[AlphaKilo470]

That's what I'd bet my money on. If the 400mhz works alright in that computer, I'd leave that and try upgrading the 770x to a PIII and getting that to work. With Intel's SpeedStep, if the CPU is working right, the minimum speed is 150mhz below the advertised speed.

[tfflivemb2]

Yeah, I knew that Speed Step drops the speed by about 150Mhz.

I have a 366Mhz in the 770X for now. Not sure that I want to open that beast again.

I think that I will just save the 750MHz and 500MHz CPUs for other 600Es that I will most likely pick up. Atleast I now know to stay away from the 55U, with regard to upgrading the CPU and Ram beyond the normal limits.

I had never had a problem with the 400MHz CPUs or the 288mb ram limit on the other 55Us that I have worked on, because I never pushed that threshold.

With as many 600/600Es as I have worked on, I had never, until now, tried to exceed the CPU limit.

On another note: This system will also only recognize 1/2 of the 256MB PC 100 Low Density Ram, and I assume that this is due to the fact that the 55U has a different BIOS than the other 600Es.

[shined]

I heard that FSB frequency of some old 600E systemboards is fixed at
66MHz even when a P-III is installed. Also know is that some old boards
can recognize only half of the memory put in the second DIMM slot. Seems
like yor machine falls into these cases.

As to how to switch the FSB to 100MHz, you have to modify the hardware
around the clock generator. I heard one guy succeeded in this mod, but
have no pointer.

As for the memory capacity problem, I never heard anyone came up with
any solution about this. You have to live with it as it is, or better think
about changing the systemboard to a newer one.

[tfflivemb2]

FWIW, here is a thread that i just found that shows the same problem and some possible fixes, just in case someone else has this problem:

http://www.wimsbios.com/phpBB2/viewtopi ... highlight=

[AlphaKilo470]

Hmm, after reading that he tried flashing a 600X BIOS, I sorta wish I had a PIII because I just thought of a few expieriments. Well, fortunatley for my poor ol' 600E, I don't, because this thing has been poked and prodded enough.

My main philsophy is "If it aint broke don't fix it" but nonetheless, it always ends up falling though, that's how I wound up with my 166mhz FrankenPad 760E/ED/XL/EL hybrid.