First post, by ChrisK
So I have this Radeon X700 card:
I bought this card some weeks ago.
At first boot the system wouldn't boot, the second and later tries it did but it always took about 4-5 seconds before the display showed a picture.
I could install drivers in Windows 98 SE and run several rounds of 3DMark (99,2k,2001).
After that I left the system for a week or two out of free time reasons. There wasn't changed anything.
Then I took the chance and played maybe half an hour on the card and then switched the system off again.
After that it didn't boot anymore. Sometimes the POST screen showed up saying that overclocking wasn't successfull.
What the ... what overclocking? The system isn't overclocked. Resetting everything in BIOS and rebooting lead to no screen at all again.
The keyboard LEDs blink as usual but that's it. No beeps, nothing.
The system works without problems with another video card.
The X700 does not post on two other systems. So I think the card itself is the culprit.
I took some measurements on the card and I think one the voltages for the video memory is wrong.
As I don't have any comparison I can't say for sure but according to the datasheet of the memory chips it is not OK.
The momory chips need two voltages: Vddc and Vddq. Both need to be 2.6V +-0.1V.
Vddc is about 2.65V but Vddq only is 2.17V.
Vddq is generated by a ISL6522 switcher just like in this schematic:
The strange thing is although Vddq is only 2.17V the feedback voltage, VDDC_FB in the schematic, is about 0.828V. That's a bit out of spec (0.8V +-1%) but could also be caused by my voltmeter.
So far this seems to be how it should be although I'm thinking it isn't correct.
Unfortunately the real feedback resistors used on my card are a bit hard to identify. One says "911", that could be 910 ohms or 866 ohms depending on the coding scheme used. But the other one isn't really identifyable. It could be "18B" which would equal 1500 ohms.
These values give: Vout = 0.8 x (1+ (1500/866) ) = 2.18V
Which is pretty much what I have measured.
But how can that be? The datasheet clearly states a Vddq of 2.6V and not 2.18V.
https://datasheet.digchip.com/216/216-24191-H … 56163CE-5-0.pdf (tab. 3/13).
So what is going on here and can this be the reason why the card doesn't POST anymore?
Before I take out my soldering iron to remove these two resistors, does anyone here have a clue or could maybe make some measurements on equivalent cards for comparison?
RetroPC: K6-III+/400ATZ @6x83@1.7V / CT-5SIM / 2x 64M SDR / 40G HDD / RIVA TNT / V2 SLI / CT4520
ModernPC: Phenom II 910e @ 3GHz / ALiveDual-eSATA2 / 4x 2GB DDR-II / 512G SSD / 750G HDD / RX470