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Go 7600 constantly varying its core/memory speed


undertoad

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Hi

I've downloaded just about every PC-analysis/driver cleaner/system tuning utility there is on the net in the last few weeks. And about 4 different nVidia driver versions.

Original problem: Company of Heroes Opposing Fronts (COHOF) is giving me the dreaded "infinite loop in nv4_disp" BSOD. Machine is a Toshiba P100-113; 2x2.0GHz; 2Gb memory; Go 7600 256Mb, 128-bit mem bus, factory-set core/memory speed 350/400 MHz; XP Pro SP3.

So I've opened up the machine, cleaned out loads of dust from the fan and heatpipe; bought a Zalman cooler; tried loads of different driver versions. And started up RivaTuner (but I'm not overclocking - no way until I get this fixed!).

Here's the weird thing. This card should run at core/memory speed 350/400MHz. This is what the Riva OC-ing page picks up, correctly (though I haven't touched those sliders).

But the great thing about Riva is the background hardware monitoring. And this is where it gets weird.

The core/memory speed, in normal Windows operation, generally sits at 0/0. Every few minutes it goes up to 199/135 or 199/199 for 20 sec, then down to 0/0 again. If I start up COHOF it goes right up to per-spec values of 351/398.

Now I just downloaded this "nv4 loop fix" file from this random Greek site (see reference here: nv4 loop fix), installed it and played a game in COHOF with Riva watching over the temps and speeds in the background.

Looking at the log file:

- Temperature never gets above 68C. That's good, isn't it?

- But, at one point, at the point where the game got busy and started stuttering (say 0.2 - 4 fps) - I noted the time - the speed dropped to 198/198. Only for 10 seconds, then back up to 351/398 again. The game was hopelessly stuttering for the following 20 minutes (I went on playing for the sake of log results).

I'd guess that the card deciding to have a rest in the middle of a COHOF game screwed the game completely for the rest of the session. I'd also guess that this is the point at which I might have got an "infinite loop" error - which this "nv4 loop fix" may have "fixed" - so at least allowing me to view a log and see what's going on. If I remember right the BSOD explanation is "driver got into an infinite loop waiting for hardware to respond" - which I guess is exactly what might happen if the GPU suddenly decides it's a bit tired and wants to run at half-speed!

Is this some kind of deranged power-management thing? I've got every setting I can find set to "screw the battery, gimme performance".

It can't be an emergency overheat shutdown, unless Riva's temperature sensing is way out: when this slowdown happened, the temperature was 64 or 65C. (Riva did record a 1-second spike of 112C during normal WIndows operation earlier, so it clearly is at least vaguely accurate). Maybe it's connected to not using the original drivers (I'm using 91.33 - Toshiba's latest are 84.4, but they gave me BSODs as well)?

Anyone have any ideas what may be causing this? I think I MAY have tracked down the cause of my infinite loop nightmares. But what to do about it?

:) :) if anyone can point me in the right direction.

Edited by undertoad
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Thats an essay and a half...

Ok basically your core and mem is fluctuating. I've had, this but only when the system is very very hot. like 90-100 0c which does not seem to be your issue. Although in saying that, every system is differnt. (i know that Dell computers run very hot.)

1) Cange the driver.

There are plenty of people using your card on here, and they will be able to tell you what version works well for that card. i use 174.74 for mine, and its mint (8600GT) should be a good place to start for u also.

remember to uninstall driver, then install your new one. Or perhaps even a clean install of XP/vista

2) BIOS update. google it to see if your system needs an update.

3) also check the GFX card bios. might need an update also.

Edited by wook
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Thanks for that wook. To go to the next step, can I get a bit more info?

1. nVidia driver: I've tried 84.4 (Toshiba's latest on their site for this machine), 91.33, 156.33 and 163.16. All of them gave me the "infinite loop" error. I'll give your recommendation of 174.74 a go tonight; but are there any Go 7600 users around who can recommend a version?

2. BIOS update. I'm right up to date with Toshiba's latest. Unless I find something better with a modded INF on a site like this one.

3. GFX card bios/firmware flash. There seems to be no sign of Go 7600 firmware or BIOS updates anywhere on the net. Anyone know where I could get this?

4. General question. The speed changes aren't really a "fluctuation" exactly, they don't wobble up and down, as if e.g. the master clock chip is clockwork, runs out of steam and needs rewinding. It's a very definite ramping up and down to exact values. Could this be some kind of insane power management? (I think the card has always done this in general Windows usage, as the ramp up is accompanied by a sudden "sigh" from the fan, which is very familiar. This is not a problem. What is a problem is the ramping down to 1/2 speed when under load in COHOF). Could it be that Toshiba sprinkle some kind of mobo-specific fairy-dust on their nVidia drivers - which of course they're not going to tell us about - so that alternative drivers, from this site for example, get the power management wrong, and ramp down the speed in the middle of a game:

- Either because the drivers think the card isn't under load; or

- because the drivers think the temperature has hit 115C, when it obviously hasn't?

5. IRQs. I recently installed XP SP3; which MAY re-detect all the hardware and assign it IRQs (machine runs ACPI unfortunately). I don't really trust IRQ-sharing (being an old DOS/Win 3.1 hand), especialy with a high-performance component like this GPU. Here's what shares the same IRQ:

IRQ 16 Shared Intel® PRO/1000 PL Network Connection

IRQ 16 Shared Intel® 82801G (ICH7 Family) USB Universal Host Controller - 27CB

IRQ 16 Shared Intel® 82801G (ICH7 Family) PCI Express Root Port - 27D2

IRQ 16 Shared Mobile Intel® 955XM/945GM/PM/GMS/940GML Express PCI Express Root Port - 27A1

IRQ 16 Shared NVIDIA GeForce Go 7600

I guess there's not a lot I can do about that except

a) Re-install XP (Oh please God no!), which will just assign another silly IRQ combination; or

:) Disable ACPI, which I'm not confident about.

Is IRQ-sharing of a GPU ever a problem in people's experience?

thanks for any ideas!

Edited by ®®®
Removed Full Quotation of Previous Post
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Well this is a complete and utter mystery.

I thought I'd run some more tests last night. Booted up the machine/space heater (that Go 7600 pumps out heat), and noticed that Riva was logging the GPU core/mem speeds at a rock-solid 351/398MHz. Never changes. That ramping up and down is just gone.

This was just before I installed the Toshiba 4.3.0 BIOS update released a couple of weeks ago. Maybe this BIOS update has a time-travel feature?

I wish I could have got to the bottom of this. But, so far, the machine is running fine on Forceware 91.33; 3DMark05 is giving me 3300-ish. Company of Heroes runs just fine, with GPU temperature never going beyond 71C.

I'm tempted to tweak and fiddle, but I'll give it a week and then start thinking about Forceware 158.22, and OC-ing.

Very strange!

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