Several sites I've looked at recommend OCZ Ultra II or AS3 Ceramique (though
they do warn that the latter is mildly conductive). But both claim they
reduce the overall temp 10°C under load. I know, to my cost, that all pastes
are not created equal, so what do you use? Also, does anyone recommend the
use of paste on a graphics card (in this case a 9700 Pro)? If so, how - and
where - do you apply it?
Also do you need a special cleaner to remove the remainder of the pad, or
will something I have readily available work?
If the heatsink is well-lapped there is very little difference between
the various compounds, except that the silicone-based ones tend to dry
out over time, making it more beneficial to reapply, sooner.
Otherwise I've heard that Shin Itsu's (Grey?) version is best, but it
more difficult to apply, more expensive, and more difficult to find,
all for a 0-1C difference over AS3, and IIRC, it IS silicone based.
There should never be a 10C difference under full load unless there's
too much compound applied or the base of the 'sink is very poor, more
likley coupled with a P4 (or other) CPU with a heat-spreader, since
this spreads out the retention force, and leave more compound
in-between the CPU and 'sink.
The conductivity of it shouldn't be an issue if applied very thinly,
but even so the ceramic-based pastes do seem to perform 1-2C worse
than AS3, though again this is with a less-than-optimal heatsink
finish. I would suggest AS3 if for no other reason that that it's
"good enough", easy to find and inexpensive in the small quantities
needed, though if you already had something else you might as well use
whatever is handy.
The main thing about thermal paste on a video card is, if it has a
depressed center like an all-epoxy chip or nVidia's with the silver
spreader in the middle, the paste needs to be fairly thick, else it
will run out, only provide partial coverage over time. The flipchip
GPUs don't have this issue. Where to apply it is simple, in the
middle of the GPU. Of course this requires a heatsink with mounting
lugs/holes, as found on almost any mid-to-high end, modern card.
Heatsink grease isn't usually of that much benefit on a video card
though, they don't have the heat-density of a CPU (yet). Several
heatsinks I've applied with AS Epoxy have no overheating problems,
overkclock to same levels others report.
The pad can usually be cleaned off with a petroleum-based solvent,
like "Goo Gone", WD-40, or just about anything that says "contains
petroleum-based..." on the label. This is in general, though some
cards seem to have some sort of epoxy-type cement, that has to
practically be sanded or scraped off with a razor blade, though that
type of adhesive is easy to spot, it is brittle instead of gummy, and
was used more often on older cards than the newer ones.
Dave
