Keith, at 19:02 on Aug 04 1996, you wrote to Bill Grimsley...

BG> What brand of board, type of chipset, and BIOS ?

KR> the only identifier on the board is the "made in china"
label. if you peel 
KR> that off, there is a label that says "made in taiwan" (:.
the chipset is 
KR> sis, the bios award.

Good, that's quite a decent board then.  Soyo actually place their own
sticker over the SIS chipset, but they are basically identical, right down
to the Award 4.50 BIOS.  Those boards can be made to run the 5x86 very
easily, even though the CPU is not directly supported.

BG> Did you try setting it up as both the Enhanced AMD DX2/66 or DX4/100 ?
BG> With the former, it should run as a quad if you pull pin 17 low, and
BG> with the latter, a normal tripler (assuming that the board doesn't
BG> actually support the 5x86, which it obviously doesn't).

KR> i have now got it working. i removed the cpu, and metered pin a17 to one of 
KR> the setup jumper pins. the manual calls out that pin for some cyrix cpus, 
KR> but not any amd models. i did this with a supposedly identical board at 
KR> work, and got a different answer. god knows what i was tying to vss (:

You're a braver man than I am, then.  I would have made sure which pins
were Vss first, but I'm glad it finally works for you (I knew it would). 
:)

KR> i have now got it running at 160mhz, even though the bios only reckons it 
KR> at 150 (just quadded and not overclocked, it reckons 120) but landmark v6 
KR> comes up with 163.949mhz. these are the landmark results:-
KR>     
KR> dx4-100 .............. 457
KR> 5x86 (33mhz clock) ... 563   (1.23x)
KR> 5x86 (40mhz clock) ... 821   (1.79x)

Yeah, those are in the same ballpark as my own LM 6.0 results, so there's
no question that despite the BIOS suggesting otherwise, it is indeed
running as a quadrupler.  Quite a fast 486-class chip too, with a 40MHz
bus.

KR> the only bugbear now is that the cpu series regulator transistor gets quite 
KR> hot. it got too hot to touch after about 2 min. i have now put a heatsink 
KR> on it and have added a cpu fan blowing on it. that makes 4 of these fans in 
KR> the box (one for the cpu, one for each hard disk, and now one for the 
KR> regulator.

That's odd.  Have you jumpered the CPU as a 3.45V device?  AMD's docos do
state that it runs at around 24W, which equates to a current of just under
6A, but the Cx6x86 is just as power-hungry, so I really wouldn't worry
about that. 

BG> FWIW, I've had my fun with the 5x86, and have just bought a Triton II
BG> 430VX motherboard and a Cyrix 6x86/100 CPU (which runs a treat at
BG> 120MHz) for a total outlay of just $300 inc tax.  That's only $100
BG> more than a 5x86 board and CPU, yet the difference in speed is
BG> staggering.  QDI have just released a similar board, which has inbuilt
BG> SCSI, so perhaps something like that might be the way to go?  Model
BG> number is P51430VX-250, and the Award PCI flash BIOS includes NCR 810
BG> and Adaptec 7850 SCSI BIOS.  Sounds very elegant to me.

KR> think that i'd better give up fixing mainframes and take up vcrs (:

I wouldn't.  You'll go broke, just like I have.  :)

KR> the p5143vx-250 sounds interesting, does it come with aspi drivers? whats 
KR> the price and from where?

All I got were the mailout flyers from QDI in Sydney, full of specs, but no
prices.  You can phone them on (Sydney) 9417-2947 (Fax 9417-3106).

KR> what do you think of the 686? i hear that it's integer performance is 
KR> excellent but that the fpu is a lot slower than the pentium, i also hear 
KR> that they dissipate noticably more heat that an equivalent pentium.

They're a HELL of a lot faster than I thought, and so far, does not appear
to be running overly warm, even at my default overclocking to 120MHz.

Here are the Landmark 6.0 figures for the Intel Triton II (430VX chipset)
board with a Cx6x86/100 CPU clocked at 100Mhz, 110Mhz, & 120MHz...

            100MHz     110MHz     120MHz       
            -----------------------------
     CPU    1188.92    1313.21    1432.61
     FPU    1154.86    1275.72    1391.75
     Vid    19660.80   20915.74   21370.43
     ID#    P-120+     P-133+     P-150+

It also runs with a bus of 66MHz (i.e. 133MHz), with a proportional
increase in performance, but whilst Win95 and DOS work fine at that speed,
OS/2 traps during bootup.  No big deal, I'm still quite happy, as the CPU
(including a huge heatsink and fan) cost just $110 ex tax.  Sure, the FPU
performance is less than the equivalent Pentium CPUs, but integer
performance leaves the Intel chips for dead, and by a bloody LONG chalk.

Regards, Bill
@EOT:

--- MsgedSQ/2 3.50