7640 & 7643 PPD

[bollix47]

FWIW

My 560 Ti current setup:

core 830 Ghz
shader 1660
memory 2004
fan 65%

No problems with these WUs except their PPD is about 30% lower than the 80xx projects.

[apeman556]

Hello, Tried the gpu at the recommended clocks last night but unfortunatley it still failed to finish a 7640 WU, again it said 'mdrun_gpu returned 52' 'NANs detected on GPU', it did however complete 8036 wu, as it always does, it only ever fails on the 7640 WU. Its not an overheating problem as I've changed the stock cooler for an Artic pro cooler and the temp only ever reaches 69 when overclocked, runs at about 50 degrees at stock speed. Any other suggestions, it does seem like that the problem is with the work unit 7640, it's the only unit that fails to finish.

[P5-133XL]

When you change coolers, you have to make sure the VRM's and/or the RAM get heat sinks too. The stock cooler had a plenum (cover) that directed air over them which gets removed when adding the replacement cooler. If you don't cool them independently it is possible to overheat the VRM's or even the RAM to the point of failure while the GPU is still plenty cool. There are no temp sensors for VRM's...

[apeman556]

hello, yes, the artic cooler came with plenty of heatsinks which I've stuck over all the vrm's and memory chips, there is also plenty of air going through the case, 3 intake fans and 3 exhaust fans, cooling is not an issue. Since my last post, the GPU has successfully completed an 8019, 2 x 8006, an 8007 and a 8010 WU's with no problem. It just seems to be the 7640 units that fail. Any other ideas or suggestions, I'm at a loss.

[7im]

764x wus are much larger and are known to push GPUs much harder than any other work units. When people have to down clock to run these, we know the WU is chewy.

Have you run memtest on that card?

[apeman556]

Hi, yes ran memtestg80 for well over 4 hours using 850MB of ram,(the most it would let me do), no errors found. When runningthe 7640 WU's, my GPU was only running at 92%. Is this normal, could that be why it keeps failing on these?

[7im]

Read back through the thread. Running at less that 100% on these WUs is normal. However, failing on these WUs when running stock GPU speeds is not normal, unless you have one of those Factory Overclocked cards. You may have to underclock the card to make it stable.

[apeman556]

My card came factory overclocked to 900MHz, I tried reducing the clock speed to the recommended speed of 822, but to still fails to finish these 7640 WU's. I've ram memtest and every other gpu, graphic card stress tester I could find and it always passes. Any other ideas, reasons you can think of? Currently I seem to be getting the 8000 WU'd which are no problem, even at the standard overclock of 900.