HP Pavilion 500-314: big problems adding external video card

Question

Looking for some help.
I recently purchased an HP Pavilion 500-314.  Specs are as follows:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c04293928&tmp_task=prodinfoCategory&cc=us&dlc=en...
The unit includes integrated Radeon R7 graphics, and comes with a 300w power supply
I purchased this unit in large part because it explicitly states that "Supports PCI Express x16 graphics cards".  I run a quad-monitor setup for my work, and have traditionally done this using an ATI Firepro 2450 card.
I have now tried three different external graphics cards, and can get none of them to work:
First attempt was with a VisionTec Radeon HD 5570 (item #900345).  This card supports quad monitor setup, and requires a minimum 250w power supply.  When I installed the card, the HP Pavilion repeatedly beeped a series of 4 or 5 (can't remember which) beeps, but refused to send an image to any video output (either onboard or the new card).
Next attempt was with an EVGA GeForce GT 610.  This is a dual monitor setup, and requires a minimum 300w power supply.  Got the same exact response as with the VisionTec (i.e. series of beeps...computer would not fire any monitors up).
So with both of these (new) cards, I basically gave up immediately as I couldn't even get into BIOS (b/c no monitors would work) to see what was going on.  My understanding is that the series of 4-5 beeps usually means that there is a graphics card issue, or that the card that has been added doesn't have sufficient power.  This is frustrating, as the HP Pavilion 500-314 supposedly has a 300w power supply, which is at least equal to the min required for each of these cards.
At this point, I pulled the ATI Firepro 2450 out of my old machine and tried it.  This card at least didn't cause the series of 4-5 beeps.  Windows booted.  However, once I log in, Windows tries to install the new (FirePro card) repeatedly, so the screen just flashes and flashes and flashes.  I then went into BIOS.  The BIOS indicates that the system is recognizing the card, and that the onboard video has been disabled.  However, there is still a signal coming out of the onboard video output (DVI), so it is not in fact actually disabled.  My sense is that Windows is trying to control two separate video cards (onboard + external), which is what is causing the problems.  I can disable the FirePro video card from w/in Windows (using Safe Mode), and leave the card installed, and things work fine.  However, as soon as I try and enable the card I get the endless cycle of flashing monitors again.
I have spent a couple of long sessions with HP tech support and they have been useless.  They claim that this isn't an HP issue since the onboard video works fine.  I find this response extremely frustrating.  I think this is an HP issue, since the BIOS doesn't seem to be properly disabling the onboard video.  Not to mention that the PC can't seem to interface properly with Windows 8 compatible PCI-E cards that explicitly claim to require less power than this unit has.
I am generally pretty computer savvy, but have reached my wits end on this one.  I would appreciate any help anybody could provide.  I have tried all kinds of combinations of variables (i.e. enabling onboard video, setting external card to primary, etc.) through BIOS, as well as combinations from w/in Windows disabling onboard video, but nothing seems to work.
VisionTek 900345 Radeon HD 5570 1GB DDR3 PCI Express 2.0 x16
This question was solved.
View Solution.

Answer 1

lordmonk3y,
Both the ATI Firepro 2450 (which never worked properly, but the system did recognize and was able to boot with when installed) and the GeForce GT 610 claim to draw right around 30w peak (closer to 20w average).  Both are considered to be relatively low-draw graphics cards, and neither is a standout performer.  My work requires a lot of available screen space, but not a lot of graphics horsepower.  I don't do any gaming.  For heavier hitting graphics cards you might want to consider a bigger power supply.  Based on most of what I looked at, 300w is the bare minimum for a lot of these cards, and many of them require a larger power supply.
For what it's worth, I looked at the specs listed on the side of the PS in the 500-314, and it actually claims peak power of 300w, but only 250w at higher operating temperatures.  It's kind of a catch-22, because if you're running a more powerful card it's sure to generate more heat inside the tower, thereby lowering the available power from the PS.
I did notice that there's one other nice thing about using an external card.  The onboard Radeon R7 grabbed 1GB of the stated 8GB system memory for itself, thereby leaving only 7GB free for system use.  Now that I'm using an external card, I get the whole 8GB available for system use.