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HD3870 faulty card/ psu / drivers?

Last response: in Graphics & Displays
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June 2, 2008 1:29:33 PM

Dear All,

I would be grateful for any help on the following.

I have just upgraded my pc with a new graphics card - the Sapphire HD3870 (from a 7600GT) and I am experiencing some odd system behaviour.

On Colin McRae Dirt (patched 1.2) - I can play for anything from 1 min to 90 mins on Ultra settings with no problems - then it freezes, screen turns blank, signal goes from the monitor and I have to reset.

On playing Assassins Creed for 90 mins+ on the highest settings, the system is stable and I have no probs.

After the crash, I looked at the clock and memory speed settings and they were set to around half the speed of the defult (720/1125).

I can run ATI tool for 30mins+ with no errors. Temps went as high as 90 degrees C.

I have a socket 939mobo - ASROCK 939NF6G-VSTA
Amd 64x2 4800+
2x1GB DDR2
1 x 160GB HD
1x DVD/CD
and a generic 480W PSU

all drivers are up to date.

From my readings of the forums it seem that my PSU might be underpowering the card causing instability. I can't think it's the card as in some situations it performs perfectly. The drivers seem pretty rubbish and I have tried the omega version but the same things happens.

I would be grateful for any ideas or wisdom.

Best,

Dan Simmonds
June 2, 2008 1:44:48 PM

Half the speed on memory is right.

DDR=double data rate, it can send data on both positive and negative edge of the clock, meaning the effective rate of transfer is equivalent to double of the actual frequency, i.e. 1125MHzx2=2250MHz.

90C is normal and these cards can withstand it. And your PSU should not be the problem unless it cannot deliver the 480W promised.

If Colin McRae Dirt is the only program that freezes I would first suspect a driver/software issue.
a b U Graphics card
June 2, 2008 1:46:44 PM

It's either getting too hot, (however 90C is not out of question for a GPU) or maybe your PSU is not supplying enough amps on the 12 volt rail. Make sure you have good case circulation. Another fan added somewhere would be an inexpensive first try to remedy the issue.
It may not be the just the GPU getting hot, It could also be your 4800.
I always say work from the bottom up, so I would add another case fan...unless of course you already have like 4 of them.
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June 2, 2008 2:08:41 PM

Wow - thanks for the lightening quick response!

derek85 - the ddr2 refers tot the RAM that slots into the mobo - the HD3870 has 512mb of ddr4 and it had displayed the correct values before the crash. As for the drivers - I reckon you might be right - it does seem to be a hell of a buggy game. It worked fine on my old 7600GT too.

jitpublisher - i did wonder about the 12 volt rail. I think it is pretty low and I have read that I would need at least 26A for the HD3870. The side is off the case so its and the probs are still occuring so can't get any breezier than that! Seeing as ATI tool pushed the temps to 90+ i can't think Dirt would be tougher?

I have got and enormous 120mm fan and a few little ones but they don't seem to do the trick.

All ideas would be welcomed.

Best,

Dan
June 2, 2008 2:22:20 PM

First thing I would suspect would be the power supply, generic 480 just doesn't do it. Frequently these cheap PS don't deliver what they advertise. Get a decent PS, its the heart of your system, without good power you will always have problems.
June 2, 2008 3:16:49 PM

Right - I did wonder. I was a bit freaked out when it first crashed as after the signal went from the monitor there was this high pitched tone. Thought it might be the card - but I guess that if it works fine with other demanding games, it can't be?

Thanks again for all ideas - please keep them coming if you have any.
June 2, 2008 3:20:10 PM

Also - if anyone can recommend a good and reasonably cheap psu, i'd be grateful. I know that the ones for 15 quid on ebay are to be avoided even if they promise 750w. Not sure I understand the concept of rails though - if a psu has one 12v rail at 19A - that's rubbish. If a psu has two 12v rails at 15A that combines to 30A on the 12v rails? Or is there a different logic?

Best, Dan.
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